Anthony Constantino leads the NY-21 Republican primary at an 80% implied probability, ahead of Assemblyman Robert Smullen at 21%, reflecting trader assessment of Constantino’s Trump endorsement and business background versus Smullen’s state legislative experience and party organizational support. The June 23 primary to replace Elise Stefanik features a tight timeline, with early voting underway and candidates intensifying outreach across the 15-county district on shared priorities including the economy, border security, and manufacturing. Recent developments include a negative ad dispute, with Smullen issuing a cease-and-desist over claims he labeled defamatory, alongside prior campaign finance complaints filed by Constantino. These dynamics, combined with Constantino’s outsider positioning and Smullen’s local ties, have shaped the current market consensus ahead of the vote.