Pivotal Politics

In general terms, pivotal politics deals with the power of political actors in a collective decision-making situation. A pivot is a person or thing around which something turns or depends, and in coalition theory, a player is said to be pivotal if its departure from a winning coalition renders the coalition nonwinning. In 1998, Keith Krehbiel proposed a formal theory of pivotal politics with a focus to ascertain who was pivotal in various lawmaking situations in the United States. This theory also explores the relationship between divided government and gridlock, where gridlock refers to political stalemate, or more specifically, an absence of policy change in equilibrium in spite of the existence of a legislative majority that favors change.

Pivotal politics theory aims at harmonizing two basic facts of U.S. lawmaking: that gridlock in the United States is not constant although common, and that coalitions are greater than simple majority and regularly bipartisan. It is based on a preference-based nonpartisan model that explains why divided government may not necessarily produce gridlock and lower legislative productivity. The theory's key argument is that veto players driven by their individual preferences are pivotal actors in the U.S. legislative process. This is in contrast with party-centered theories that stress the importance of partisanship in affecting lawmaking, gridlock and legislative productivity and social choice theories such as median voter theorem that stress centrifugal forces in creating policies.

The theoretical model recognizes that legislation in the United States must pass many veto players before it becomes law. The players include legislators and a president functioning in a bicameral legislature. We simplify in Figure 1 to a unicameral legislature (we can see the two houses agreeing on a single line through the joint committee system) where each player has an ideal point along a unidimensional liberal-conservative policy space. Players prefer a policy over the status quo if that policy is closer to their ideal point. According to the theory, policies are adopted according to the preferences of players who are at crucial pivot points in the policy space, rather than those who are at median position. This happens because in the U.S. lawmaking process the president's right to veto and the right of extended debate (filibuster) temper the politicians' capacity to enact policies. The pivot-point legislators are those who can overturn or uphold a veto when the president disagrees with the position of the legislature, or who can break a filibuster if the president and a majority of the Senate agree but a significant number of senators favor status quo. Figure 1 illustrates the key idea behind the pivotal politics theory more clearly.

Figure 1 Pivotal actors with a conservative U.S. president

Source: Based on Keith Krehbiel, Pivotal Politics, Figure 2.2, p. 23. University of Chicago Press (1998). Copyright 1998 by University of Chicago Press. Used with permission.

In this example, there are 11 legislators and a conservative president in the legislature. The key pivots are the filibuster pivot and the veto pivot, whose ideal points are represented on the liberal-conservative policy space. The other two players are the president and the median voter, with their respective ideal points also depicted on the policy space. The president is on the right side of the median voter, and therefore, the veto pivot is the [Page 481]legislator whose ideal point and all ideal points toward his left equal two thirds of the legislature. Thus, the fourth voter from the right is the veto pivot. Similarly, with the president being on the right side of the median voter, the filibuster pivot is the legislator whose ideal point and all ideal points on his right equal three fifths of the legislature. Here, the filibuster pivot is the seventh voter from the right. The pivotal politics theory also captures the tendency of U.S. lawmaking to gridlock where the president opposes policy change that congressional majorities favor in light of the two-thirds override provision.

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