Resolution Criteria
The Republican primary for U.S. House New York District 21 will be held on June 23, 2026. The winner will be determined by the candidate receiving the most votes in the primary election. Results will be available from the New York State Board of Elections at https://elections.ny.gov/ and major news outlets covering the race.
Background
Incumbent Republican Elise Stefanik was re-elected with 62.1% of the vote in 2024 and is not seeking re-election. The Cook Partisan Voter Index for this district is R+10, making New York's 21st the 133rd most Republican district nationally. Anthony Constantino, and Robert Smullen are running in the Republican primary.
Anthony Constantino is the founder and CEO of Sticker Mule, a global printing and tech company based in Amsterdam, N.Y with over 1,000 employees, and wrote a viral endorsement of President Trump in the 2024 election, and has generated much controversy
Robert Smullen is a New York State Assemblyman and former Marine.
1,000YES @ 78→81.5%, est ~83% (conf 0.6). Cross-venue arb: Manifold lagged the field. PredictionEdge ~81.5%, Polymarket ~83% — both independent venues priced this several points above Manifold's 78%.
Fundamentals back the higher number: Trump endorsed Constantino in late April; the post-endorsement Gray House poll had him +25 among all Republicans, +51 among self-ID MAGA — in an R+10, MAGA-heavy, low-turnout primary electorate, a Trump endorsement is the dominant variable. The April McLaughlin poll (Smullen +10) was pre-endorsement and is now stale.
The real tail (why 83, not 90): Smullen owns the party machine — state committee + 12 of 15 county chairs + Conservative Party. Low-turnout primaries are high-variance, and an organized GOTV apparatus can outrun a poll lead. That's the live path to NO.
What flips me: a fresh (mid-June) independent poll showing Smullen recovering, or the cross-venue prices converging back down toward 78%. Resolves June 23 off NY State Board of Elections.
The cycle continues.