Plurality winners in primaries hurt parties, new paper finds
New research finds that when candidates win primary elections with less than 50% of votes, they perform worse in general elections than candidates who win their primaries with a majority. In competitive districts, this translates to a reduced likelihood of winning the general election. Majority-rule nominating methods like ranked choice voting (RCV) can help parties perform better.
For example, in 2022, Republicans lost a slew of competitive elections after advancing nominees who won their primaries with a minority (or “plurality”) of votes. Those include Doug Mastriano’s bid for Pennsylvania governor, Blake Masters’s bid for Arizona’s U.S. Senate seat, and Mehmet Oz’s bid for Pennsylvania’s U.S. Senate seat. We wanted to discover whether these examples are part of a broader pattern that affects both Democrats and Republicans.
In a database of U.S. House, U.S. Senate, and gubernatorial elections from 2010-2022, we found that winning the primary election with a plurality is associated with a statistically significant decline in general election performance. Plurality winners are expected to perform 1.47% worse than majority winners, relative to expectations. The effect persists regardless of the type of party, place, or race.
When focusing on competitive general elections, we found that plurality primary winners are 11.3 percentage points less likely to win the general election. This effect is roughly half the size of the “incumbency advantage” – the effect of facing or being an incumbent in the general election. It suggests that this is a substantively meaningful predictor of who wins the general election.
Parties could benefit from implementing ranked choice voting for primary elections. RCV sends majority-supported nominees to general elections, helping more voters feel invested in their party’s nominee. For example, the Virginia GOP used RCV to choose its 2021 gubernatorial candidate. Glenn Youngkin won 33% of voters’ first choices, but his vote share grew to 55% by the final round of the RCV count. Youngkin went on to win a competitive general election, becoming the first Republican to win statewide in Virginia since 2009.
Plurality primary winners are problematic for democratic representation and choice. Thankfully, parties may be more likely to change the status quo if they can see the damage to their interests. This paper shows that plurality winners are indeed harmful to parties, and could give them reason to implement RCV.
Professor Laurel Harbridge-Yong and I co-authored the paper, titled The Plurality Problem: Plurality Primary Victors Hurt Parties in General Elections. It is now available on the Social Science Research Network (SSRN) and Northwestern University’s Institute for Policy Research.
