“I don’t think the average person knows how liberal Gretchen is,” said Randy Richardville, a former Republican senate majority leader from Monroe, who did battle with Ms. Whitmer during her days in the legislature. “ I don’t think it will be a cakewalk for her at all.”

Still, these Monroe voters say they are amenable to politicians who appreciate the union way of life and genuinely seem to want to protect it.

“I’m union all the way,” said Darryl Sims, a United Automobile Workers member from Monroe County who retired last year as a forklift driver at Detroit Diesel. “I’m very appreciative when I walk out every month and my pension is in the mail.

Mr. Sims has a favorable view of Mr. Trump, citing the president’s approach to trade and “his philosophy that we should take care of our own people.” His wife, Michele, a teacher, believes the president has done a good job as well.

But they are quick to distinguish between Mr. Trump and Michigan Republicans like the outgoing governor, Rick Snyder, whom they criticize for deciding to tax their pensions and enacting right-to-work legislation, allowing workers to benefit from unions without paying dues or fees.

“They swore up and down they wouldn’t do it,” Mr. Sims said.

A voter outreach project last fall by the Service Employees International Union, which canvassed thousands of pro-union white working class voters in Michigan and Wisconsin, showed that voters like Mr. Sims are very much in play. The top issues, even among many who vote Republican, were good-paying jobs and expanded access to health care.

Unions in the state are trying to seize this opportunity by increasing field workers, volunteers and campaign spending — in some cases, even at greater levels than during the last presidential race.