Ambition and Party Loyalty in the U.S. Senate 1

Ambition and Party Loyalty in the U.S. Senate 1 Sarah A. Treul Department of Political Science University of Minnesota Minneapolis, MN 55455 streul@umn.edu April 3, 2007 1 Paper originally prepared for presentation at the 2007 Annual Meeting of the Midwest Political Science Association.

Abstract This paper examines the role progressive ambition plays in the U.S. Senate. More specifically, this paper analyzes the effect ambition has on party loyalty in the upper chamber. The theoretical argument is that senators with ambition for higher office may have higher party unity scores than their colleagues who never make a bid for higher office. This is because of their need to appeal to the party before running for the presidency with the hopes of winning the party s presidential nomination. This paper posit two primary hypotheses in order to test this theory. Hypothesis 1 : Since a senator needs to win his party s primary in order to gain higher office, a senator who seeks higher office will be more likely to vote with the party on party votes than those senators who never run for the presidency. Hypothesis 2 : As a senator approaches his bid for higher office, he becomes increasingly likely to vote with the party on party votes. Both of these hypotheses are confirmed. These findings indicate that ambitious senators are more loyal to the party than their unambitious colleagues.

Introduction Despite the Founding Fathers never intending for parties to play a role in American government, the fact is that political parties play a central role in American democracy. As Schattschneider claimed, political parties created democracy, and...democracy is unthinkable save in terms of parties (1942). Although Schattschneider was correct that parties play a role in all aspects of democracy, the research on American parties is often synonymous with the study of Congress. The focus on parties in Congress makes sense, as Congress was designed to be the strongest link between the governed and the government. Unfortunately, for most scholars working in this area, Congress has been synonymous with House of Representatives, as stunningly little literature has focused on the upper chamber the U.S. Senate. The primary reason for the lack of scholarly research on the Senate is that the technical models used to examine House behavior have not travelled well to the upper chamber. In contrast to the House, the Senate has a weak presiding officer and the Senate s rules provide less structure on floor proceedings. Each senator including the leader of each party is a formal equal, so party identification is often less significant than in the lower chamber. Further, the six year term in office insulates senators from constant electoral pressure faced by their House counterparts. These institutional constraints have made it difficult for models of the House to work for the Senate, and yet, no model of congressional procedure or behavior is complete without taking into account the upper chamber. Recently, the most compelling debate in the Congressional literature has been over 1

the effect of legislative parties on the behavior of party members (Rohde 1991; Cox and McCubbins 1993, 2005; Krehbiel 1993, 1998). A central finding of the parties matter side of this debate is that in the House, the majority party exerts its greatest influence on legislative proceedings through its cartel like control over the legislative agenda. While the party effects literature is extensive, there has been a dearth of attention given to the role of parties in the Senate (but see Cox, Campbell and McCubbins 2002; Brady 2002). There is some evidence to suggest that party effects are present in the Senate, but they are very different and varied than party effects observed in the House (Lawrence et al. 2005). Furthermore, the literature on parties needs to address the opposite question what effect do individual party members have on the party? This question is especially salient in the Senate, as many individual party members aspire to hold higher office. For instance, a senator who is considering a run for the presidency may desire to play it safe while simultaneously appealing to a broad constituency. That is, the senator may attempt to keep both his current constituency content at the same time he seeks to expand his appeal nationally. This paper seeks to put the Senate back into models of party government. The goal is to model the effect ambitious senators have on party cohesion within the Senate. More specifically, I will show how ambition for higher office affects party loyalty within the chamber. All the while, this paper will address a larger question: Does party matter in the Senate? 2

Parties in Congress Current scholarship on Congressional procedure and party effects in the House emphasizes the role parties play in helping members overcome collective action problems through delegation to a central authority (Olson 1965; Aldrich 1995; Cox and McCubbins 1993, 2005). Without parties, legislators face a chaotic and unpredictable agenda, and thus, legislators form parties to join themselves together into reliable coalitions (Schwartz 1977; Aldrich 1995; Smith and Gamm 2001). Another theory of party formation is that parties are created primarily to reap electoral gains. In this case, parties provide politicians with a brand name in order to ensure that the typical problems associated with providing a public good are overcome, and that legislative actions can foster valuable reputations (Cox and McCubbins 1993; Kiewiet and McCubbins 1991; Cox 1987; Evans and Oleszek 2002; Strøm 1990). An alternate theory as to why we see party formation in legislatures depicts parties as firms or partnerships. All of these theories emphasize the role of party leaders. These models involve the delegation of authority to party leaders in order to reduce collective action problems and minimize transaction costs (Alchian and Demsetz 1972; Sinclair 1983, 1995; Stewart 1989; Rohde 1991; Maltzman and Smith 1994; Binder 1997; Cox and McCubbins 1993; Gamm and Smith 2002). Once parties are formed, the best-known model to explain how parties disciple their members is the conditional party government model (Aldrich 1995; Rohde 1991; Aldrich and Rohde 2001). This model posits that more power is delegated to party leaders when the differences between the parties vary more than the distances within the party. In conditional party government 3

the majority party is cohesive, disciplined, and decisive (Krehbiel 1993). While the conditional party government model contributes to our understanding of responsible party government, another theory is based on the majority party s ability to control the legislative agenda. No partisan theory has been more influential in the field than the work of Cox and McCubbins (1993, 2005), which views parties as procedural coalitions. Cox and McCubbins contend that the majority party in the House exerts strict control over the legislative agenda through the Committee on Rules. In their view, the majority party rarely has to twist arms of wayward members to win on policy, it simply uses agenda control to keep issues that will divide the party off the House floor. As current House Speaker Dennis Hastert (R-IL) has said, the Speaker s job [as party leader] is to construct the agenda in such a way as to please the majority of the majority [and] is not to expedite legislation that run counter to the wishes of his majority. 1 In procedural cartel theory, parties control the agenda through strict party discipline. According to Cox and McCubbins, when party leaders have the means to impose discipline on party backbenchers, agenda control is attained by the extension of the will of the party leadership (1993, 19). When discipline is costly, parties use both positive and negative agenda control. Positive agenda control is when parties control the agenda by allocating proposal rights (Laver and Shepsle 1996; Diermeier and Fedderson 1998). Negative agenda control is when parties control the agenda by allocating veto rights among their members (Tsebelis 2002; Cox and Poole 2002). Cox and McCubbins (2005) extend this theory of agenda control by defining the key resource that majority 1 Speech given by Hastert on November 12, 2003 at the Library of Congress. 4

parties delegate to their senior partners as the power to set the legislative agenda. This model views parties as procedural cartels, which monopolize the agenda by creating and filling agenda-setting offices, filling the agenda with bills that will not split the party and that most in the party will support, and getting rank and file Congressmen to support the agenda (Cox and McCubbins 2005). This model posits a strong and cohesive party a party that votes as a block. Although the work of Cox and McCubbins clearly articulates how this process works in the House, there is little mention of the Senate. The Cox and McCubbins model does not directly translate to the Senate due to the Senate s inability to completely control its own agenda (e.g. the Senate must put presidential nominations and House budget legislation on its agenda, the filibuster empowers every senator). Therefore, party cohesion in the Senate cannot be explained via agenda-setting the same way it can in the House. This paper posits that in order to explain party cohesion in the Senate (or lack thereof), scholars need to look at the role ambition for higher office (i.e. the presidency) plays in the upper chamber and its effect on party cohesion. By analyzing the role ambition plays in the Senate and, more importantly, how it affects party cohesion, we can begin to have a clearer picture of what party means in the Senate. That is, we can begin to develop a picture of when party in the Senate looks like party in the House and when it might look and function quite different from the lower chamber. Research on the causes of political ambition has been conducted since the 1960s when Joseph Schlesinger wrote about three different types of ambition in his classic 1964 study 5

Ambition and Politics: Political Careers in the United States. For Schlesinger, a political actor who seeks higher office is labelled as having progressive ambition. Progressive ambition is the primary concern of this paper. 2 Expanding on Schlesinger s model of the causes of ambition, Rohde (1979) developed a model to predict when a member of the House would run for higher office (i.e. when a member should be ambitious). This model is an improvement over Schlesinger s model because Rohde uses a sample of all members not just those who sought higher office. Brace (1984) confirms and furthers Rohde s study by showing that there are important factors, including electoral vulnerability and risk acceptance, that help determine whether a member will run for higher office. Extending this rational choice model to the Senate, it is likely that senators are more prone to make a bid for the presidency when the costs or running are low, the candidate has no potential liabilities, and the candidate is risk acceptant. While research on the factors contributing to (i.e. the causes of) political ambition is prolific (see for example Brace 1984; Rohde 1979), little has been done with regard to the consequences of political ambition. In one of the first studies on the consequences of progressive ambition, Hibbing (1986) shows that ambitious House members alter their roll call voting behavior in the two years leading up to the election and that these same House Congressmen participate less on floor votes. Victor (n.d.) extends Hibbing s work and examines the effect of ambition on Congressmen s other types of legislative behavior 2 Schlesinger also examines what he labels discrete and static ambition. Both of these types of ambition suggest a satisfaction with the status quo and therefore are not examined here. Herrick and Moore (1993) have added a fourth type of ambition to Schlesinger s work: institutional ambition. This type of ambition has to do with the Congressman s desire to hold leadership positions within the chamber. However, since this paper deals with ambition in the Senate and each senator, even those holding leadership positions is a formal equal, this type of ambition will not be addressed here. 6

(constituency service, committee service, floor speeches, etc.) in the U.S. House. By accounting for other types of legislative behavior, she finds that higher office seekers engage in more legislative activity than the non-ambitious. Although both Hibbing and Victor s work sheds light on the consequences of political ambition, it only looks at the House and neglects to take party into account. Clearly, to the extent that there is a literature on political ambition, it is inconclusive at best. Literature on the consequences of political ambition shows Congressmen who run for higher office participate in significantly fewer roll-call votes (Hibbing 1986) and are too constrained to be legislatively active in their current office (Matthews 1960), while simultaneously showing higher office seekers engage in more legislative activity than their less ambitious colleagues (Herrick and More 1993). In order to correct this incongruence in the literature, this paper develops a more complete model of the consequences of ambition a model that captures more than just a Congressman s success at attaining higher office. After all, if ambition is a personality construct, as Schlesinger suggests, it should not matter whether or not the ambitious office-seeker is electorally rewarded in his bid for higher office. Thus, this study expands past work on ambition, looking not just at the way ambition affects the legislative behavior of individual Congressmen, but rather how ambition does or does not affect the entire party within the chamber. Although prior research on the consequences of ambition is somewhat mixed, the theoretical argument that ambitious senators affect party cohesion in the Senate is compelling. First, studies in psychology tell us that ambition is a personality construct and 7

is, therefore, seen in an individual s behavior (Herrick and More 1993; Hibbing 1991). Thus, senators with ambition for the presidency are likely to behave differently than those without such ambitions. Senators seeking the presidency should want to expand their audience and eventually their constituency, whereas, senators content with their present position should simply want to please their current constituency. As Schlesinger notes,...the central assumptions of ambition theory is that a politician s behavior is a response to his office goals (1966, 6). This suggests that an ambitious senator must engage in behavior that will make him a national figure and win him national backing, and not just a single-state constituency. Senators who seek the presidency will continue to engage in Mayhew s (1974) position taking, credit claiming, and advertising, but they must partake in these activities in such a way that simultaneously allows them to reach out to a broader audience. Second, there is some evidence that party affects roll rates in both the House and Senate, despite the agenda control process working differently in the two chambers (Lawrence et al. 2005; Cox and McCubbins 2005; Cox and Poole 2002). That is, party affects the majority party s ability to win on legislation. Knowing this, it seems plausible that a senator who sees himself as a future president may affect the party s ability to control the agenda and legislate effectively. If ambitious senators are courting a national constituency, they may be more inclined to buck the party line on certain roll calls, adversely affecting party cohesion. Is it possible that ambition for higher office could explain roll rates in the Senate? 8

Hypotheses The theoretical argument that ambitious senators are apt to appeal to a national constituency may suggest that they will have lower party unity scores as they get closer to running for the presidency. That is, as a senator recognizes the need to appeal to a broader audience he may become more moderate on party votes. However, it is equally likely to posit that senators with ambition for higher office may have higher party unity scores, as they attempt to appeal to the party with the hopes of winning the party s presidential nomination. After all, in the age of the primary, it is necessary to convince the party that one is the best candidate in order to have the opportunity to convince the general electorate. Keeping this in mind, the theory here suggests that ambition affects party cohesion in a positive direction. Stemming from this theory, I test two primary hypotheses: Party Loyalty Hypothesis: A senator who runs for the presidency will vote differently than her colleagues who do not make a bid for the presidency. Additionally, since the senator needs to win her party s primary in order to gain higher office, the directional expectation is that those senators who seek higher office will be more likely to vote with the party on party votes to appeal to primary voters. Strength of Party Loyalty: As a senator approaches her bid for higher office, she becomes increasingly likely to vote with the party on party votes. 9

Data In order to test these hypotheses, I analyze U.S. senators from 1963-1965 with the goal of capturing an entire senator s career and not just the time immediately before a presidential campaign. This is crucial for ambition theory because, as Schlesinger notes, ambition may only become evident when examining an entire career. I select my cases by using the freshman class of senators from the 88th-107th Congresses. Each of the senators in the analysis was elected between 1962 and 2002 the freshman classes of the 88th (1963 1965) through the 107th (2003 2004) Congresses. 3 While it can be argued that all senators enter their careers with aspirations for the presidency, in reality, this data set of freshman senators will provide an array of levels of ambition. 4 During this time period there were 258 freshmen senators. Figure 1 shows the number of freshman senators in each of the Congresses. Of the 258 senators examined, 32 make a bid for the presidency, with nine making it onto a presidential ticket (either as a presidential or vice presidential candidate), and 23 running in a presidential primary. 5 [Figure 1 about here] 3 Senators who had previously been in the Senate were excluded. 4 I chose not to include freshman classes beyond the beyond the 107th because I thought it important that each of the senators in the study complete a full term in the Senate. Any senator elected after the 107th Congress is yet to have completed a full term in the Senate. 5 If a senator made a bid for higher office more than once, I coded their first attempt at running for the presidency. Recognizing that this is leads to a relatively static model, I also model the number of years until the senator ran for office, hoping to create a more dynamic model. This will be discussed in more detail later. 10

Analysis Unit of Analysis: The unit of analysis is senator senates. That is, each senator in each Senate. The Dependent Variable: The dependent variable is the senator s Party Unity score. According to Poole and Rosenthal (1997) a party unity vote is defined as one where at least 50 percent of Democrats vote against at least 50 percent of Republicans. The expectation is that loyalty to the party on party votes will depend on whether or not the senator is progressively ambitious. The Independent Variables: The primary independent variable of interest is political ambition. This was initially measured as an ordinal variable, but in order to make the results more meaningful I created dummy variables for each category. 6 Also included in the one or more of the models is the absolute value of the senator s Nominate score, time until bid for higher office, and dummy variables for divided government, whether or not the senator is a member of the majority party, and whether or not the senator is a party leader. I use the Ordinary Least Squares (OLS) regression estimator to model the relationships between the explanatory variables and party loyalty. The estimated coefficient and its corresponding standard error are reported in Tables 1, 2, and 3. 6 The original variable was coded 1 6 with 1 representing those senators who never ran for higher office, 2 being those who ran in a presidential primary, 3 equalling senators who won the party s nomination for vice president, 4 representing those senators who won their party s presidential nomination, 5 being those who were elected to the office of vice president, and 6 representing those who were elected as president. 11

Results The results in Table 1 reveal that someone who goes from being a complete moderate to an extremist would have an increase in party unity of 65.51, holding everything else equal. 7 This makes sense from a Downsian perspective, as it indicates that the more extreme a senator, the more likely she is to vote with the party on party votes. Also from the model, we can see that divided government significantly decreases party loyalty. This is probably indicating that under divided government senators may be more likely to compromise in order to pass legislation. Furthermore, being a member of the majority party or being a party leader significantly increases a senator s party unity score. The explanatory variable most essential to the Party Loyalty hypothesis is whether or not the senator ran for higher office. This estimate explains the effect of political ambition on party unity. According to the model, running for higher office, at any point in time, leads to a 2.55 unit increase in a senator s party unity score as compared to those senators who never make a bid for higher office. 8 This suggests that those senators who run for the presidency are more likely to vote with the party. [Table 1 about here] Table 2 presents the results for the model that takes into account how successful the senator is in his bid for higher office. In this model, a dummy variable is created for four of the five ordinal categories representing how far the senator progressed in his presidential 7 Fixed effects for each Congress were also estimated, but are not reported in the table. 8 Party unity is measured on a 0-100 scale. The party unity mean for senators in the data set is 81.70 with a standard deviation of 16.15. 12

campaign. The results indicate, similarly to the results from Table 1, that running in a presidential primary increases a senator s party unity score by 2.43 units, as compared to the senator s colleagues who did not enter a presidential primary. Additionally, gaining the party s nomination corresponds with a 2.76 increase in the senator s party unity score. 9 This suggests that those who are loyal to the party are more likely to last through the primary season and gain the party s approval. Lastly, the senator s success in obtaining higher office increases his party unity score by 3.36 units. 10 However, this result is not significant, which could indicate that while being a party loyalist may help the senator proceed through the primary season, party loyalty may be insignificant when trying to win the White House. [Table 2 about here] The last model estimated only examines those 254 senators who ran for higher office. These results can be seen in Table 3. This model adds a time variable, in an attempt to make the results more dynamic. The time variable captures the number of congresses away the senator is from making his bid for the presidency. The coefficient indicates that as the time increases, the senator s party unity score decreases. That is, the farther away from their national campaign the senator is, the less likely he is to vote with the party on party votes. As the senator s campaign for higher office approaches he becomes increasingly likely to vote with the party. 11 Also interesting to note is that divided government has 9 This variable includes those senators who were on the party s presidential ticket as either the presidential or vice presidential candidate. 10 This variable includes winning the vice presidency. No senators in this sample were successful in winning the presidency. 11 This result is not significant with a p-value of 0.063. 13

little effect for those senators who run for higher office, suggesting that senators who run for higher office are no more or less likely to vote with their party depending upon the type of government. The same effect is also found for being a member of the majority party. 12 [Table 3 about here] Discussion The results indicate that senators who run for higher office are more loyal to the party on party votes than their colleagues who do not make a bid for the presidency. Furthermore, those senators who advance further in their bids for the presidency have higher party unity scores than those senators who never advance beyond the party s primary. This finding suggests that progressively ambitious senators, who are also the most successful in their bid for higher office, have higher party unity scores. This could be because senators who hope to one day find themselves in the White House recognize the importance of the party in helping them reach their goal. That is, senators who come into the Senate with progressive ambition recognize the importance of the party when it comes to successfully navigating the primary season. These findings confirm the Party Loyalty Hypothesis, which posits that since a senator needs to win her party s primary in order to gain higher office, the directional expectation is that those senators who seek higher office will be more likely to vote with the party on party votes to appeal to primary voters. 12 Although these the coefficients for divided and majority are not significant, they still have an interesting interpretation. 14

Additionally, the model indicates that as the senator s bid for higher office approaches, her party unity score increases. Again this indicates that senators recognize the importance of party when it comes to reaching their ultimate goal of the presidency. Also, following an unsuccessful bid for higher office and a return to the Senate, her party unity score again decreases as additional time passes. This finding is not significant, but the direction is consistent with the hypothesis which contends that as a senator becomes closer to making her bid for higher office, she is increasingly likely to vote with the party on party votes. Although I recognize that there may be an endogeneity problem in this analysis, I suggest that because Schlesinger s theory (1964) suggests that ambition is a personality construct and not something created overtime, ambition is nascent. For this reason, it seems unlikely that party loyalty leads to ambition. After all, it is unlikely that a senator needs to be convinced to run for higher office or comes into office without any plans for the future. By taking progressive ambition into account in the Senate, this paper shows that party may be just as successful at influencing votes in the Senate as it is in the House. Future research on the work of party loyalty in the Senate needs to address the effect ambition has on party cohesion. That is, does having numerous ambitious senators in any given Congress increase the effect of party? Is progressive ambition a potential tool the party can use to control its members? Additionally, future work on ambition in the Senate should address other ways of measuring ambition besides party votes. 15

Overall, this paper puts the party back into the Senate by adding progressive ambition as a tool the party can use to achieve the votes it needs. Ambitious senators, especially those who turn out to be the most successful, are more loyal to the party than their colleagues who never make a bid for higher office. Recognizing the importance of the party in winning the presidential primary, progressively ambitious senators have higher party unity scores than senators who do not run for the presidency. This research also has electoral implications, as it suggests that senators are aware that the electorate rewards party loyalty. 16

Figure 1: Ambitious Senators by Congress Congress Total Number of Freshman Ran for Higher Office 88th 14 5 89th 9 2 90th 9 2 91st 13 2 92nd 14 3 93rd 17 2 94th 12 1 95th 22 2 96th 16 2 97th 19 1 98th 5 0 99th 9 5 100th 13 2 101st 12 2 102nd 8 0 103rd 15 0 104th 12 0 105th 14 0 106th 10 1 107th 15 0 Total 258 32 17

Table 1: Running for Higher Office and Party Loyalty Variable Coefficient (Std. Err.) Ran for Higher Office 2.554 (0.735) Abs. Value Nominate 65.509 (1.593) Divided Govt. -2.635 (0.558) Majority Party 2.139 (0.549) Party Leader 6.547 (2.324) Intercept 59.025 (0.744) N 1550 R 2 0.557 F (5,1544) 388.162 18

Table 2: Higher Office Success and Party Loyalty Variable Coefficient (Std. Err.) Abs. Value Nominate 65.495 (1.597) Divided Govt. -2.649 (0.560) Majority Party 2.131 (0.550) Party Leader 6.512 (2.340) Ran in a Presidential Primary 2.427 (0.850) Party s Pres. Candidate 2.760 (1.396) Won Higher Office 3.359 (2.917) Intercept 59.040 (0.747) N 1550 R 2 0.557 F (7,1542) 276.94 19

Table 3: Time before Running and Party Loyalty Variable Coefficient (Std. Err.) Abs. Value Nominate 60.549 (4.047) Divided Govt. -0.112 (0.905) Majority Party -1.451 (0.896) Party Leader 5.181 (2.360) Time -0.211 (0.113) Intercept 64.273 (1.751) N 254 R 2 0.48 F (5,248) 45.751 20

References Alchian, Armen A., and Harold Demsetz. 1972. Production, Information Costs, and Economic Organization. The American Economic Review 62(5):777 795. Aldrich, John H. 1995. Why Parties? The Origin and Transformation of Party Politics in America. Chicago, IL: University of Chicago Press. Aldrich, John H., and David W. Rohde. 2001. The Logic of Conditional Party Government. In Congress Reconsidered ( Lawrence C. Dodd, and Bruce I. Oppenheimer, editors), Washington D.C: Congressional Quarterly, volume 7th, pp. 269 92. Binder, Sarah A. 1997. Minority Rights, Majority Rule: Partisanship and the Development of Congress. Cambridge: Cambridge University Press. Brace, Paul. 1984. Progressive Ambition in the House: A Problematic Approach. Journal of Politics 46:556 71. Cox, Gary W., and Mathew D. McCubbins. 1993. Legislative Leviathan: Party Government in the House. Berkeley, CA: University of California Press. Cox, Gary W., and Mathew D. McCubbins. 2005. Setting the Agenda: Responsible Party Government in the U.S. House of Representatives. Cambridge: Cambridge University Press. Cox, Gary W., and Keith T. Poole. 2002. On Measuring Partisanship in Roll-Call Voting: 21

The U.S. House of Representatives, 1877-1999. American Journal of Political Science 46(3):477 89. Diermeier, Daniel, and Timothy J. Fedderson. 1998. Cohesion in Legislatures and the Vote of Confidence Procedure. American Political Science Review 92:611 21. Gamm, Gerald, and Steven S. Smith. 2002. Policy Leadership and the Development of the Modern Senate. In Party, Process, and Political Change in Congress: New Perspectives on the History of Congress ( David Brady, and Mathew D. McCubbins, editors), Stanford, CA: Stanford University Press, pp. 287 311. Herrick, Rebekah, and Michael K. More. 1993. Political Ambition s Effect on Legislative Behavior: Schlesinger s Typology Reconsidered and Revisited. Journal of Politics 55(3):765 76. Hibbing, John R. 1986. Ambition in the House: Behavioral Consequences of Higher Office Goals Among U.S. Representatives. American Journal of Political Science 30(3):651 665. Hibbing, John R. 1991. Congressional Careers: Contours of Life in the U.S. House of Representatives. Chapel Hill, NC: University of North Carolina Press. Krehbiel, Keith. 1993. Where s the Party? British Journal of Political Science 23(2):235 66. 22

Krehbiel, Keith. 1998. Pivotal Politics: A Theory of U.S. Lawmaking. Chicago, IL: University of Chicago Press. Laver, Michael, and Kenneth A. Shepsle. 1996. Making and Breaking Governments: Cabinets and Legislatures in Parliamentary Democracies. Cambridge and New York: Cambridge University Press. Lawrence, Eric D., Forrest Maltzman, and Steven S. Smith. 2005. Who Wins? Party Effects in Legislative Voting. Legislative Studies Quarterly Forthcoming. Maltzman, Forrest, and Steven S. Smith. 1994. Principals, Goals, Dimensionality, and Congressional Committees. Legislative Studies Quarterly 19(4):457 76. Matthews, Donald R. 1960. U.S. Senators and Their World. New York: Random House. Olson, Mancur. 1965. The Logic of Collective Action. Cambridge, MA: Harvard University Press. Poole, Keith T., and Howard Rosenthal. 1997. Congress: A Political-Economic History of Roll Call Voting. Oxford University Press. Rohde, David W. 1979. Risk-Bearing and Progressive Ambition: The Case of Members of the United States House of Representatives. American Journal of Political Science 23(1):1 26. Rohde, David W. 1991. Parties and Leaders in the Postreform House. Chicago, IL: University of Chicago Press. 23

Schwartz, Thomas. 1977. Collective Choice, Separation of Issues and Vote Trading. American Political Science Review 71:999 1010. Sinclair, Barbara. 1983. Majority Leadership in the U.S. House. Baltimore, MD: Johns Hopkins University Press. Sinclair, Barbara. 1995. Legislators, Leaders, and Lawmaking: The U.S. House of Representatives in the Postreform Era. Baltimore, MD: Johns Hopkins University Press. Smith, Steven S., and Gerald Gamm. 2001. The Dynamics of Party Government in Congress. In Congress Reconsidered ( Lawrence C. Dodd, and Bruce I. Oppenheimer, editors), CQ Press, volume 7th, pp. 245 69. Stewart, Charles. 1989. Budget Reform Politics: The Design of the Appropriations Process in the House of Representatives, 1865-1921. Cambridge: Cambridge University Press. Tsebelis, George. 2002. Veto Players: How Political Institutions Work. Princeton, NJ: Princeton University Press. Victor, Jennifer Nicoll. n.d. The Consequences of Ambition for Higher Office: Examining U.S. House Memnbers Legislative Behavior 1970-2004. Paper presented at the Midwest Political Science Association Meetings in 2004 and 2005 and the American Political Science Association Meeting 2004. 24