State Treasurer Stacy Garrity commands 95.4% implied probability in the Pennsylvania Republican gubernatorial primary market as the sole candidate on the May 19 ballot, bolstered by the Pennsylvania GOP's endorsement in September 2025 and party unity following Sen. Doug Mastriano's January decision against a rematch bid. No other Republicans qualified for ballot access by the March deadline, leaving write-in efforts—like a grassroots campaign for Mastriano launched in early April and nominal support for Lt. Gov. hopeful John Ventre—as long-shot alternatives with scant traction amid low visibility. Recent voter registration drives and Garrity's campaign events underscore her momentum ahead of the May 4 registration cutoff. Scenarios to upend this include an unprecedented write-in surge outpacing her votes or a late-breaking scandal, though historical primaries favor uncontested ballot nominees.