Same-Party Candidates, Fewer Votes? Examining Undervoting after Top-Two Primaries Adoption

The adoption of the Top-Two Primary system in California (2012) and Washington shifted primary access but potentially fractured general election voting.

🗳️Undervoting Effects: Voters without an affiliated candidate in either party—called Orphan Voters—were significantly more likely to undervote, especially when both major-party candidates remained in the race. Compared to voters with a copartisan candidate on the ballot, these Orphaned Voters showed nearly 20 percentage points higher rates of not voting.

🧠Voter Decision Models: A two-step framework explains this behavior:

• Partisan Model: Voters unable to select their top choice party in the general election more likely abstain or undervote.
• Ideological Model: All voters are influenced by ideological proximity, preferring candidates they perceive as closer ideologically regardless of partisan barriers. Those who vote tend to see less distance between themselves and the candidates than Orphaned Voters do.

🔍Real-World Impact: These findings illuminate how ballot construction influences voter turnout even among those with strong preferences.