Trader consensus on Polymarket positions Michael Minogue as the frontrunner at 53% implied probability to win the Massachusetts Republican gubernatorial primary on September 1, propelled by his campaign-commissioned Pulse Decision Science poll in early March showing him dominating the field among likely GOP primary voters. Brian Shortsleeve trails closely at 39.5%, buoyed by a recent high-profile endorsement from U.S. Sen. Tom Cotton on April 6 and his prior leads in late 2025 polls like Boston Globe/Suffolk. Mike Kennealy lags at 9%, having slipped from an early UMass poll advantage amid intensified competition. With the Massachusetts GOP convention just 10 days away on April 25—where candidates need 15% delegate support to secure primary ballot access—momentum from recent debates, town halls, and attacks on Gov. Maura Healey's affordability policies could shift odds further in this closely contested three-way race.