Legislative Coalitions, Polarization, and the U.S. Senate

In recent years, scholars have marshaled a vast amount of evidence to show that the congressional parties are increasingly polarized. However, David Mayhew demonstrated that most standard legislative enactments in the second half of the twentieth century passed with the support of large majorities of both parties. This article investigates whether the partisan polarization of the past two decades has crept into the temple of consensual lawmaking that hitherto characterized Senate action on final passage votes. The findings reveal that unilateral votes by one party are better explained by unified government than the rise of partisan polarization. In that light, the import of polarization may be overstated. Institutional features of the political system, coupled with the electoral incentives of lawmakers, offset ideological polarization at the final passage stage of important legislation.