Will anyone win the Senate Republican primary election in the first round

30-day trend

Analysis

This probability reflects whether a Republican Senate primary candidate will secure their party's nomination on the first ballot or vote at the nominating convention, rather than requiring a subsequent round. The 56% estimate suggests markets view a first-round victory as slightly more likely than a contested outcome. The wide 33-percentage-point gap between trading venues indicates disagreement about nomination dynamics and delegate behavior. Key drivers include the strength and consolidation of frontrunner support, the number and viability of competing candidates, and rules governing delegate allocation across state parties. The outcome becomes clearer as state Republican parties hold their nominating conventions and primaries, with major decisions typically occurring through spring and early summer 2026.

• ›Republican Party rules for 2026 require specific delegate thresholds for first-ballot nomination success, which vary by state party apparatus rules
• ›Number of declared major candidates and their relative delegate counts as conventions approach will directly determine first-ballot viability
• ›State-by-state primary and convention calendar timing affects when sufficient delegates are allocated to enable or prevent first-round settlement
• ›Delegate pledge behavior and defection rates in actual voting versus pre-convention commitments determine whether frontrunner support holds
• ›Kalshi's higher probability (60%) versus Polymarket (27%) suggests material disagreement about whether nomination rules favor quick resolution

What moved the line

• May 7Senate Republican primary↓10pp29→19¢ · Kalshi
• May 7Lt. Governor Republican primary↓10pp14→4¢ · Kalshi
• May 6Senate Republican primary↓8pp37→29¢ · Kalshi
• May 6Lt. Governor Republican primary↓8pp22→14¢ · Kalshi
• May 6Governor Republican primary↓6pp15→9¢ · Kalshi

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These markets stopped trading. Last odds and any captured outcome are shown above — full settlement detail lives at the venue.

How we compute these odds