The Role of Political Parties in the Organization of Congress: Theory and Evidence

Abstract

This paper considers a model of political two-party competition over multiple policies when each policy is the domain of a particular legislative committee. Each party is composed of members who differ in their ideological preferences over policies but who have similar weightings of the importance of particular policies. Each committee acts to select policies in its own domain, subject to approval by the floor. The parties select committee memberships to maximize the density-weighted joint utility of its members, subject to institutional restrictions on committee compositions. Parties may choose either to accommodate or confront one another in committee assignments. For issues of importance to only one party, accommodation is shown to be the optimal strategy, and the committee appears as a classical preference outlier. For policies important to both parties, confrontation occurs, and the committee membership will be a bipolar preference outlier. Interest group ratings data from the U.S. House of Representatives are utilized to support this theory.