Gov. Gretchen Whitmer of Michigan, a leading Democrat from a critical battleground state, on Wednesday subtly warned against President-elect Donald J. Trump’s tariff threats targeting Canada, even as she stressed her broader willingness to work with him on the cusp of his second inauguration.
Her speech, at the Detroit Auto Show, offered among the clearest examples yet of how Democrats from states that Mr. Trump carried are seeking to balance fresh overtures to the incoming president with their staunch opposition to some of his policy proposals.
Speaking at a convention center just across the Detroit River from Windsor, Ont., Ms. Whitmer described strong cultural and industrial ties between the two cities.
Using tariffs as punishment, she said, risks “damaging supply chains, slowing production lines and cutting jobs on both sides of the border.”
Ms. Whitmer did not mention Mr. Trump by name as she broached the subject, but he has threatened to impose tariffs on imports from Canada if the country does not reduce the flow of migrants and fentanyl to the United States. The Ontario Premier Doug Ford has discussed retaliation, including threatening to disrupt the electricity supply from the province to the United States.
“I am not opposed to tariffs outright, but we cannot treat them like a one-size-fits-all solution, and we certainly shouldn’t use them to punish our closest trading partners,” Ms. Whitmer said, arguing that such an approach could embolden China.
“They would love nothing more than for us, to watch us cripple America’s auto ecosystem all by ourselves,” she said. “This is a matter of national security.”
Ms. Whitmer also noted that components of automobiles often cross the U.S.-Canada border more than once in the production process. Tariffs imposed each time, she suggested, could mean “you’ll pay more to buy a Silverado, fix the engine of your Mustang, or replace the fender on your Jeep Grand Cherokee.”
The comments were part of a wide-ranging speech about her economic vision and about responding to the challenges and competition confronting Michigan’s auto industry, both internationally and from other states. The broader industry accounts for 20 percent of Michigan’s work force and contributes $304 billion to the state’s economy annually, according to the Detroit Regional Chamber.
“We must stay nimble to support businesses that are already here and win new ones, too,” she said. “We can’t just unilaterally disarm, like some on the far left and far right would have us do.” She told Republicans that to truly fix the state’s roads, new revenue would be necessary, while telling Democrats that “fiscally responsible cuts” were also needed.
Throughout, Ms. Whitmer peppered her remarks with promises to work on a bipartisan basis both locally and nationally, an approach that has taken on new urgency after Democrats in November lost control of the Michigan House of Representatives.
She also extended those gestures explicitly to Mr. Trump, who flipped Michigan in November, four years after President Biden won the state.
Noting that Michiganders had twice supported both herself and Mr. Trump, Ms. Whitmer said, they “expect us to find common ground.”
Ms. Whitmer’s comments stood in contrast to the more combative stances that elected officials from some deeply Democratic states have taken.
“I don’t want to pretend we’re always going to agree, but I will always seek collaboration first,” said Ms. Whitmer, who has clashed for years with Mr. Trump. “I won’t go looking for fights. I won’t back down from them either.”
In an interview on Tuesday, Ms. Whitmer said she wanted to “redouble my efforts to connect with him after the inauguration.”
“President Trump cares about Michigan, he spent a lot of time here in Michigan and Michigan helped elect him to the White House,” she said of a man who has often been described as susceptible to flattery. “I want to make sure that we don’t take our eye off the ball and that we are really focused on using tariffs as a scalpel and not a, you know, a sledgehammer.”
During her speech, Ms. Whitmer walked a careful line on a hot-button issue in the state: the transition to electric vehicles. She said the definition of the auto industry had expanded to include not only part makers and assembly plants, but also “battery factories, software companies, chip fabs and startups.”
“We don’t care what you drive,” she said to applause. “We just care that it’s made right here in Michigan, by Michigan workers.”