Michael Minogue secured the Massachusetts Republican Party endorsement at the April 2026 state convention with over 70 percent of delegate votes, establishing him as the clear frontrunner for the September 1 primary. Former MBTA leader Brian Shortsleeve narrowly cleared the 15 percent threshold to remain on the ballot, while former Baker administration official Mike Kennealy fell short at 14 percent and suspended his campaign days later. Party officials and RNC members have since pressed Shortsleeve to withdraw and consolidate support behind Minogue ahead of the general election against Democratic incumbent Maura Healey. Traders assign Minogue an 82 percent implied probability of winning the nomination, reflecting his dominant convention performance, substantial self-funding, and alignment with the party base, while Shortsleeve holds a modest 9.8 percent chance as the sole remaining challenger on the ballot.