Gov. Larry Hogan of Maryland signaled on Wednesday that he opposed the gubernatorial candidate backed by Donald Trump, the latest escalation of a proxy war between the term-limited Republican governor and the former president.

Hogan, whose exit from office represents one of the best pickup opportunities for Democrats in November, said that Trump “selfishly colluded” with a Democratic funding group to back state Del. Dan Cox in a move that could cost Republicans a governorship this fall.

“Trump lost Republicans the White House, the House, and the Senate,” Hogan wrote on Twitter. “He’s selfishly colluded with national Democrats to cost us a Governor’s seat in Maryland where I ran 45 points ahead of him. He’s fighting for his ego. We’re fighting to win, and the fight goes on.”