Gov. Rick Snyder of Michigan will not support Donald J. Trump, his party’s presumptive presidential nominee, making him the latest prominent Republican to distance himself from the party’s new de facto leader.

“I’ve stayed out of the whole thing, and I’m going to continue to,” Mr. Snyder told The Detroit News editorial board on Wednesday at the Mackinac Policy Conference. “I’ve got important things I want to work on in Michigan.”

Mr. Snyder told the paper that his focus is on keeping a Republican majority in the state’s House of Representatives. “We’ve had a great partnership there, and I think it’d be great to continue that,” he said.

Mr. Snyder has faced his own struggles in his state amid the elevated lead and contamination in the water in Flint and extensive criticism that he mishandled the response.