The United Auto Workers, in a first, is striking against GM, Ford, and Stellantis at the same time. Expect the union’s demands — including pension changes and raises to keep pace with inflation — to threaten President Biden in key states as President Trump champions the blue-collar cause.

The “Stand Up Strike” isn’t a traditional work stoppage, but mirrors new trends in society and politics. Instead of everyone walking off the job, the UAW chooses local chapters to act, giving them “maximum leverage and maximum flexibility … to win a fair contract at each of the Big Three” according to their website.

Cost-of-living adjustments — which the UAW gave up in 2007 when inflation was flat — have emerged as a key issue. Higher prices under Mr. Biden have driven down real wages, the union says, even as profits rose, car prices hit all-time highs, and the pay of chief executives soared by as much as 40 percent.

The UAW also seeks to restore two key benefits surrendered during the Great Recession. Employees hired since 2007 are ineligible for retiree health care and have only 401(k) plans, not the pensions that have long been a staple of union membership.

“Every day,” the head of the AFL-CIO, Liz Shuler, tweeted, “autoworkers give their hearts and souls to these companies, working to earn them exorbitant profits. This fight isn’t just about auto workers and their families, this is about creating a future where everyone can prosper!”

 Once upon a time, labor leaders could have focused their membership’s ire on Republicans alone. Today, the strike may throw a spanner into Mr. Biden’s reelection plans. Ms. Shuler is painting a picture that undermines Mr. Biden’s boasts about being “the most pro-union president in American history” who delivered a booming economy.

 Meanwhile, Mr. Trump has been riding shotgun with the UAW. On Telegram, he called Mr. Biden’s push for electric cars “a disaster for both the United Auto Workers and the American consumer.” EVs “will all be built in China,” he said, and the UAW “will be wiped out, along with all other autoworkers in the United States.”

Mr. Biden will want to put himself in the driver’s seat, too, but that carries risks. Agree with UAW’s complaints, and he trashes his own record, but a rosy scenario will sound like, “You Never Had It So Good,” the Democratic Party’s slogan in 1952 that saw their candidate lose by 11 points.

As the challenger, Mr. Trump is the better positioned of the two. In 2016, he “outperformed among union members,” as Politico reported in 2020. At the time, Mr. Biden was trying to reverse those gains with little success “especially the building trades … despite the efforts of labor leaders to convince members otherwise.”

Mr. Trump’s statement on Wednesday reflects this new reality. “Stand strong against Biden’s vicious attack on American labor and American auto workers,” it read. Adding that a vote for Mr. Trump is one for “more jobs, higher wages, and soaring pensions,” he urged members to “have your leaders endorse me.” In 2016, he used similar outreach to win Michigan, the first Republican to do so in 28 years.

Although Mr. Biden flipped the Wolverine State in 2020, Mr. Trump has put Democrats on notice that they can no longer take union members for granted. Plus, as the incumbent this time around, Mr. Biden is the face of the economy and UAW are seen as victims of its shortcomings.

More than union members are at risk if Mr. Biden is seen as among the villains of the standoff and hurting the UAW. In a poll two weeks ago, Gallup found approval for labor unions at 67 percent. A record 61 percent say unions help the economy and 75 percent side with the union over automakers.

The UAW strike helps Mr. Trump shine a spotlight on the economy’s weaknesses even as Mr. Biden touts its strengths. If negotiations stall and the pain spreads, the Democrats may end up like used car salesmen, trying to sell that lemon of a slogan, “You Never Had It So Good” to an electorate that prefers a smoother ride and decides to hand the wheel back to Mr. Trump.