Nudging Democrats to Cross Over: GOTV Boosts GOP Primary Turnout in New Hampshire

Why This Matters

Primaries shape who appears on the general-election ballot, and crossover voting—voters participating in an opposing party's primary—can influence which candidate secures a party’s nomination. Hayley M. Cohen and Daniel B. Markovits study whether targeted mobilization can induce Democratic-leaning voters to vote in the 2024 New Hampshire Republican primary to blunt a candidate they fear.

The Experiment

• A large, preregistered field experiment (N = 83,800) was run in the lead-up to the 2024 Republican presidential primary in New Hampshire in partnership with a Political Action Committee.
• The intervention was a specialized get-out-the-vote (GOTV) message aimed at undeclared voters who the researchers model as likely to support Democratic candidates in the general election.
• The design randomized exposure to the GOTV treatment and tracked subsequent turnout in both the Republican and Democratic primaries; pre- and post-primary surveys supplemented administrative turnout data to assess candidate support among crossover voters.

Key Findings

• The GOTV intervention increased turnout in the Republican primary among the targeted Democratic-leaning undeclared voters by 1.6 percentage points.
• It simultaneously reduced turnout in the Democratic primary among the same sample by 0.5 percentage points.
• Survey and administrative data imply that each Democratic-leaning vote cast in the Republican primary had between a 78% and 95% probability of going to the relatively moderate Republican primary candidate.

What This Shows

The evidence indicates that some voters can respond to mobilization in a strategically sophisticated, risk-mitigating way: targeted messages can nudge oppositional-leaning voters to cross over in an open primary and, in this case, disproportionately support a more moderate nominee. The study demonstrates both the practical potential and the normative questions raised by organized efforts to influence nomination contests through crossover turnout.

Who Did the Work

The article reports results from Hayley M. Cohen and Daniel B. Markovits, published in the American Journal of Political Science, using a rare large-scale, preregistered field experiment on primary crossover voting in the United States.