President Biden announced that he would travel to Michigan on Tuesday to “join the picket line” with members of the United Automobile Workers who are on strike against the nation’s leading automakers, in one of the most significant displays of presidential support for striking workers in decades.
“Tuesday, I’ll go to Michigan to join the picket line and stand in solidarity with the men and women of U.A.W. as they fight for a fair share of the value they helped create,” Mr. Biden wrote on Friday on X, the site formerly known as Twitter.
The trip is set to come a day before Mr. Biden’s leading rival in the 2024 campaign, Donald J. Trump, has planned his own speech in Michigan, and was announced hours after Shawn Fain, the union’s president, escalated pressure on the White House with a public invitation to Mr. Biden.
“We invite and encourage everyone who supports our cause to join us on the picket lines, from our friends and family all the way to the president of the United States,” Mr. Fain said in a Friday morning speech streamed online.
It was not immediately clear where Mr. Biden would go in Michigan. The White House had already announced plans for Mr. Biden to fly to California on Tuesday as part of a three-day trip to the West Coast. Mr. Biden made the decision on Friday, after Mr. Fain’s public invitation, according to two people familiar with the White House deliberations.
Mr. Fain on Friday announced the expansion of the U.A.W.’s work stoppage from three facilities to 38 assembly plants and distribution centers in 20 states, including six — Michigan, Wisconsin, Pennsylvania, Nevada, North Carolina and Georgia — that are expected to be presidential battlegrounds in next year’s election.
Michigan, the home of the American automotive industry, is home to the bulk of the facilities and striking workers.
There is little to no precedent for a sitting president joining striking workers on a picket line.
Seth Harris, a former top labor policy adviser for Mr. Biden, said he was not aware of any president walking a picket line before.
“This president takes seriously his role as the most pro-union president in history,” Mr. Harris said. “Sometimes that means breaking precedent.”
Earlier Friday, Mr. Biden’s re-election campaign posted on social media a video of Republican presidential candidates and Fox News anchors bemoaning his support for unions. The caption from Mr. Biden read: “Yes.”
Mr. Fain’s invitation came a week into an expanding work stoppage by autoworkers at Ford, General Motors and Stellantis plants. The union president announced on Friday that the strike, which began last week at three plants in the Midwest, would expand to 38 more locations in 20 states across the country. He said that talks with General Motors and Stellantis had not progressed significantly, but that Ford had done more to meet the union’s demands.
Mr. Biden has defended the striking autoworkers since the stoppage began last week, and the White House has dispatched Julie Su, the acting secretary of labor, and Gene Sperling, a top White House economic adviser, to seek an end to the strike.
Mr. Biden has referred to himself as “the most pro-union president in American history” and has long made his alliances with and support for organized labor a central part of his political identity. But his administration’s push for a transition to electric vehicles has put him at odds with the U.A.W., because electric vehicles require fewer workers to produce.
The U.A.W. has broken with other major unions in so far declining to endorse Mr. Biden’s re-election bid.
Mr. Trump is skipping next week’s Republican presidential primary debate and instead delivering a speech in Michigan before current and former union workers. Mr. Trump pulled away significant portions of union workers from Democrats in his 2016 victory by denouncing international free trade agreements. In his current campaign, he has staked out a position against the federal push for more electric vehicles.
Jason Miller, a senior adviser to the Trump campaign, said Mr. Biden would not be going to Michigan if Mr. Trump had not announced a trip there first. On social media, he called Mr. Biden’s visit “nothing more than a cheap photo op as he finds himself between a rock and a political hard place.”
Senator Tim Scott of South Carolina — who, like the rest of the Republican presidential candidates, trails far behind Mr. Trump — sought to inject himself into the news cycle about the strike this week by suggesting that the autoworkers should be fired, a move the companies are legally prohibited from carrying out.
On Thursday, the U.A.W. postured back by filing a complaint against Mr. Scott with the National Labor Relations Board (such complaints are often dismissed). On Friday, Mr. Scott called the U.A.W. “one of the most corrupt and scandal-plagued unions in America” and said the union’s contract proposal would lead to government bailouts.
Mr. Fain, who appeared at a rally with Senator Bernie Sanders of Vermont when the strike began, has been critical of Mr. Trump and Republicans.