Principles of Politics Exercise


Goals of This Exercise

  • Define “party voting” and “party unity” as measures of partisanship in Congress.
  • Examine how Congress members’ multiple goals sometimes provide consonant- and cross-pressures that affect their votes on the House and Senate floors.
  • Illustrate the rise of congressional party voting over recent years and consider some potential causes of the fluctuations of congressional partisanship over time.

Measuring Congressional Partisanship

Party Voting and Party Unity scores are measures of institutional partisanship commonly used by scholars.

A party vote is one in which at least 50 percent of the members of one party vote against at least 50 percent of the members of the other party. Thus in any given year we can calculate the percentage of all congressional floor votes that meet this measure of partisanship. (For example, in 1972, only 27.1 percent of roll call votes in the House of Representatives were party votes; party votes were nearly twice as likely in 2008 when 53.3 percent of roll call votes were party votes.)

In addition, the average party unity score measures the internal cohesion of each party on such partisan votes.

Examining the Rationality Principle

The Rationality Principle: all political behavior has a purpose. All political actors engage in instrumental acts designed to further their individual goals.

Whereas party voting and party unity are institutional measures of partisanship, they are aggregations of the voting behavior of goal-oriented individual members of Congress.

What Goals do Members of Congress Pursue?

Most Congress scholars follow Richard Fenno’s observation that Members of Congress pursue three main goals:

  • reelection
  • influence in Washington
  • good public policy

Still, the presence of multiple goals means that members often must choose among competing demands and reconcile contradictions among their goals.

Answer the following questions:

1. Whereas most scholars acknowledge that members have multiple goals, many nevertheless argue that “reelection” is the main pursuit of members of Congress. Why is reelection often considered the primary goal of members?
2. Can you think of ways in which members’ reelection, influence, and policy goals might come into conflict? How might such conflicts affect members’ partisan voting behavior?

Party Followership and Members’ Goals

In some instances, a member’s policy and reelection goals might be consonant (or consistent) with following the party line. Yet in other cases, a legislator’s goals for reelection and achieving good public policy might be advanced better by defying party leaders.

Consonant Pressures. When constituents’ views, a member’s own policy views, and broader party goals are aligned, they all provide consonant pressures on members to support the party.

Cross-Pressures. When constituents’ views, policy views, and the member’s party are at odds, we can think of members as being “cross-pressured” and therefore facing difficult choices that will sometimes lead to following the party and in other instances voting against the party.

Contemporary examples:

Republican members who represent conservative districts and states are more likely to support conservative party policy, whereas Republican members who represent more moderate districts and states are more likely than their conservative colleagues to vote with Democrats.

Republican seat gains in the 2010 elections (gains made in districts that are generally more moderate than most Republican districts and had previously been held by Democrats) brought to the House of Representatives a number of “cross-pressured” members. In fact, there are dozens of House Republicans representing districts that President Obama won in 2008.

Changes in the district-level basis of partisanship

In the 1950s, many Democratic members of Congress were “cross-pressured” by the differing interests and ideological orientations of their congressional districts and the interests and ideological orientations of their national parties.

  • Southern Democrats, for example, represented congressional districts that were consistently conservative though their national party was increasingly liberal.
  • Issues such as civil rights, labor legislation, Lyndon Johnson’s “great society” programs, and Vietnam divided liberal Democrats from the conservative southern base of the party.

As a result of these cross-pressures and the consequent divisions within the majority party, party voting in the House and Senate declined from the 1950s to the 1970s.

Party Voting in Congress, 1953 – 1974

Source: CQ Almanac 2004 (Washington, DC: Congressional Quarterly Press, 2005), p. B-21.

The Rise of Partisanship in the House and the Senate

The contemporary Congress — both the House and Senate — has become much more partisan since the 1980s.

Key to the development of partisanship in Congress has been the increased “nationalization” of partisanship in states and districts, which has increased the consonant pressures on many House members and Senators.

According to scholars like David Rohde, changes in congressional districts and states, most notably in the South where the 1964 Civil Rights Act and the 1965 Voting Rights Act empowered African American voters, led both to a strengthened Republican Party in the South and to southern Democrats (those that remained, at least) who were more liberal.

  • Thus, as the Democratic Party was losing its conservative wing and becoming more liberal, the Republican Party was gaining many conservative southern seats, thus increasing the power of conservatives in the GOP.
  • As House and Senate parties became more ideologically homogeneous, there was a greater basis for collective partisan action and congressional partisanship (both in terms of party voting and party unity) began to rise.

With more consistently partisan districts and states, members’ re-election goals, policy preferences, and interest in gaining influence provide increasingly consonant pressures to support party initiatives.

Party Voting in Congress, 1953 – 1974

Source: Shawn Zeller, “2008 Vote Studies: Party Unity — Parties Dig in Deep on a Fractured Hill” CQ Weekly December 15, 2008, p. 3332, 3338.

Party Voting in Congress, 1953 – 1974

Source: Shawn Zeller, “2008 Vote Studies: Party Unity — Parties Dig in Deep on a Fractured Hill” CQ Weekly December 15, 2008, p. 3332, 3338.

Examining the Collective-Action and Institution Principles

The Collective-Action Principle: all politics is collective action.

The Institution Principle: institutions routinely solve collective-action problems.

Thinking of the legislative parties in the House and Senate as organizations designed to solve collective-action problems that arise among goal-oriented members of Congress, answer the following questions:

3. What are the incentives for members of Congress to be free riders in party efforts? Do some members of Congress have greater incentives to free ride than others?
4. How might party leaders and organizations help alleviate or “solve” these collective-action problems?
5. How can the collective-action and institution principles be applied to explain the changes in party voting illustrated in the preceding figures?


  • Cooper, Joseph, and David W. Brady, “Institutional Context and Leadership Style: The House from Cannon to Rayburn” American Political Science Review 75 (1981) 411-25.
  • CQ Almanac 2004 (Washington, DC: Congressional Quarterly Press, 2005).Fenno, Richard F., Jr., Congressmen in Committees. Boston: Little, Brown, 1973.
  • Rohde, David W. Parties and Leaders in the Postreform House. Chicago: University of Chicago Press, 1991.
  • Zeller, Shawn, “2008 Vote Studies: Party Unity — Parties Dig in Deep on a Fractured Hill” CQ Weekly December 15, 2008, pp. 3332, 3338.

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