Spatial models of policymaking have evolved from the median voter theorem through the inclusion of institutional considerations such as political parties, committees, and various voting and amendment rules. Such models, however, implicitly assume that no policy is more effective than another at solving public policy problems and that all proposers are equally capable of advancing proposals.

Minozzi and Volden advance the idea that a substantial portion of partisan voting activity in Congress is a simple call to unity that is especially easily embraced by ideological extremists. If correct, Minozzi and Volden’s findings should extend from the House to the Senate, despite differences in institutional structures and in tools at the disposal of party leaders across the two chambers.