Seeking more of the voters who first paved his way to the White House in 2016, former President Donald J. Trump rallied at a Michigan auto parts factory on Wednesday night, setting up a clash of messages aimed at blue-collar workers one day after President Biden appeared on a strike line with United Automobile Workers.
Mr. Biden affirmed Tuesday his support for U.A.W. strikers’ demands for a 40 percent pay raise, while Mr. Trump has given no indication that he backs the union’s position. In his appearance at a nonunion factory on Wednesday, Mr. Trump was almost certain to revisit a spate of recent attacks on U.A.W. leadership, as he seeks to drive a wedge between rank-and-file workers and their leaders.
Coming at the same time that other Republican primary candidates are debating on national television in California, Mr. Trump’s appearance outside Detroit sends the message that he has all but moved on from his lower-polling rivals and is focused on the potential for a rematch with Mr. Biden in 2024.
Mr. Trump visited Drake Enterprises in Clinton Township, north of Detroit. The company’s 150 employees make gearshift levers for heavy-duty trucks, as well as components that go into cars made by General Motors and Ford. Its president, Nathan Stemple, said it was a nonunion shop.
The Trump campaign said it expected more than 500 plumbers, pipe-fitters, electricians and autoworkers to attend. In the evening before the former president took the stage, a few hundred people were seated on the floor of the factory, and at least one man in a red U.A.W. T-shirt said he was a union member and voiced support for the strike. The Trump campaign made no effort to recruit attendees through U.A.W. locals, according to the union.
Hours after appearing with Mr. Biden on a picket line on Tuesday outside a G.M. facility in Belleville, Mich., Shawn Fain, the president of the U.A.W., told CNN: “I find a pathetic irony that the former president is going to hold a rally for union members at a nonunion business.”
Mr. Fain denounced Mr. Trump’s lack of support during a strike against G.M. in 2019 when he was in office and said he had no plans to meet with the former president during his visit.
Mr. Trump has long sought to separate rank-and-file union members from union leaders, who largely endorse Democrats. He has had notable success: He won about four in 10 votes from union households in 2020, according to exit polls.
Mr. Trump was all but certain to repeat his recent attacks on the Biden administration’s push for electric vehicles and to revisit a claim he made that autoworkers were “being sold down the river by their leadership.” The U.A.W., which argues that the transition to electric vehicles is inevitable and that it is driven by consumer demand, seeks to ensure that zero-emission vehicles are made by workers earning union wages.
On Tuesday, as Mr. Biden became the first president of modern times to join a picket line, Mr. Trump issued a statement predicting that “in three years there will be no autoworker jobs” if Mr. Biden’s policies prevail, but that “with me, there will be jobs and wages like you’ve never seen before.”
Marick Masters, a professor of business with a focus on labor issues at Wayne State University in Detroit, said the economic uncertainty around the transition to electric vehicles worried many autoworkers, providing Mr. Trump with a political opening.
“There’s a big question about how successful these companies are going to be in the transition to electric vehicles,” he said. “Trump’s message resonates, and it cuts across a broad swath of workers.”
Mr. Stemple, Drake’s president, said a too-rapid switch to electric vehicles would decimate his family company. He noted that electric vehicles did not require gearshift levers, one of his main products. “A lot of shops like us wouldn’t survive that transition if it happened rapidly,” he said.
Jason Walsh, executive director of the BlueGreen Alliance, a group that seeks common ground between unions and environmentalists, said Mr. Trump’s claim that the E.V. transition would drive American jobs to China “is almost exactly backwards.”
“What the Biden administration is trying to do is actually bring jobs back from China by investing in revitalizing American auto manufacturing,” he said.
Mr. Trump’s record with autoworkers is decidedly mixed. During his term, he pressured automakers to keep their factories in the United States rather than Mexico. Auto manufacturing jobs climbed in his first year in office, before flattening and dipping — and then the pandemic sent them plunging. Under Mr. Biden, auto jobs have exceeded their highest level under Mr. Trump.
In addition to the location, the county in which Mr. Trump plans to appear carries political symbolism: Macomb County, north of Detroit, was home to the original “Reagan Democrats,” the blue-collar voters who in the 1980s deserted the party that had traditionally advanced their standard of living, in favor of Republican messaging coded in racial division.