Department of Political Science

Washington and California adopted the Top-Two Primary in 2008 and 2012, respectively. Under this new system, all candidates regardless of party affiliation run against each other, narrowing the field down to the top two for the general election. In some jurisdictions, the general election features two candidates from the same party. Ten percent of California voters chose not to vote in the 2016 U.S. Senate election which featured two Democrats. Using data from the Cooperative Congressional Election Study (2012–2016), I find that among those who vote in the national November elections, orphans, or voters without a copartisan candidate on the ballot are more likely to undervote, opting out of voting in their congressional race. Levels of undervoting are nearly 20 percentage points higher for orphaned voters compared to non-orphaned voters. Additionally, voters who abstain perceive more ideological distance between themselves and the candidates compared to voters who cast a vote. These findings support a multi-step framework for vote decisions in same-party matchups: voters are more likely to undervote if they are unable to vote for a candidate from their party (partisan model), but all voters are more likely to vote for a candidate when they perceive ideological proximity (ideological model).