Partisanship, Ideology, and Senate Voting on Supreme Court Nominees

Ideological concerns play a major role in determining whether a senator will vote to confirm or reject a Supreme Court nominee. Much less is understood, however, about the effects of partisanship on confirmation votes. This study investigates two aspects of partisanship: first, whether confirmation voting has become more partisan over time, even when controlling for other factors, including ideology; and second, whether partisanship modifies the influence of ideology. The results demonstrate that partisanship has played an increasing role over time and that the effects of ideology are contingent on partisanship.