Parties, Coalitions, and the Internal Organization of Legislatures

45 Pages Posted: 24 Jun 2008 Last revised: 26 Jan 2011

Date Written: December 1, 2010


We present a model of parties-in-legislatures that can support partisan policy outcomes despite the absence of any party-imposed voting discipline. Legislators choose all procedures and policies through majority-rule bargaining and cannot commit to vote against their preferences on either. Yet, off-median policy bias occurs in equilibrium because a majority of legislators with correlated preferences has policy-driven incentives to adopt partisan agenda-setting rules - as a consequence, bills reach the floor disproportionately from one side of the ideological spectrum. The model recovers as special cases the claims of both partisan and non-partisan theories in the ongoing debate over the nature of party influence in the U.S. Congress. We show that: (1) party influence increases in polarization, and (2) the legislative median controls policymaking only when there are no bargaining frictions and no polarization. We discuss the implications of our findings for the theoretical and empirical study of legislatures.

Keywords: party influence, legislative organization, endogenous agenda-setting rules, coalitions, U.S. Congress

JEL Classification: D72, D78, C72

Suggested Citation

Diermeier, Daniel and Vlaicu, Razvan, Parties, Coalitions, and the Internal Organization of Legislatures (December 1, 2010). Available at SSRN: or

Daniel Diermeier

Northwestern University - Kellogg School of Management ( email )

2001 Sheridan Road
Evanston, IL 60208
United States

Razvan Vlaicu (Contact Author)

Inter-American Development Bank ( email )

1300 New York Ave NW
Washington, DC 20577
United States

University of Maryland ( email )

3114 Tydings Hall
College Park, MD 20742
United States

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