Rarely do so many parts of a president’s political identity collide in one place.

Friday’s walkout by the United Auto Workers is a real-time test of President Biden’s economic agenda: his call for higher wages for the middle class; his unapologetic pro-union stand; his climate-driven push to reimagine an electric vehicle future for car companies — centered in Michigan, a state that he must win in 2024 to remain in the Oval Office.

The targeted strike by some members of the 150,000-member union is designed to disrupt one of America’s oldest industries at a time that Mr. Biden is sharpening the contrast between what rivals and allies call “Bidenomics” and a Republican plan that the president warns is a darker version of trickle-down economics that mostly benefits the rich.

“Their plan — MAGAnomics — is more extreme than anything America has ever seen before,” Mr. Biden said on Thursday, just hours before the union voted to strike.

At the White House, Mr. Biden’s aides believe the outcome of the battle between the car companies and its workers will underscore many of the president’s arguments about the need to reduce income inequality, the benefits of empowered employees, and the surge in profits for companies like the automakers that makes them able to afford higher salaries.

“You’ve got rebuilding the middle class and building things again here,” said Eddie Vale, a longtime Democratic strategist who for years worked for the AFL-CIO. “You’ve got green energy, technology and jobs. You’ve got important states for the election. So all of these are sort of together here in a swirl.”

“If not handled correctly, there are policy and political risks,” Mr. Vale said, but added: “In the end, Biden is going to be able to play a role as an honest broker here.”

Those risks were already beginning to be evident Friday morning. In a searing statement, the head of the U.S. Chamber of Commerce laid blame for the strike at Mr. Biden’s feet.

“The U.A.W. strike and indeed the ‘summer of strikes’ is the natural result of the Biden administration’s ‘whole of government’ approach to promoting unionization at all costs,” said Suzanne P. Clark, the president of the nation’s largest business lobbying group.

She predicted the strike will have “far reaching negative consequences for our economy.”

Unlike previous strikes involving rail workers or air traffic controllers, Mr. Biden has no special legal authority to intervene. In the current situation, he is not in control, though not exactly just an observer either.

Just before the strike vote, Mr. Biden called Shawn Fain, the president of the U.A.W., as well as top executives of the car companies. Aides said that the president told the parties to ensure that workers get a fair contract and he urged both sides to stay at the negotiating table.

That did not happen. Economists say a lengthy strike, if it goes on for weeks or even months, could be a blow to the American economy, especially in the middle of the country.

How Mr. Biden navigates the situation could have a significant impact on his hopes for re-election. In a CNN poll earlier this month, just 39 percent of people approved of the job he is doing as president and 58 percent said his policies have made economic conditions in the United States worse, not better.

The fact that the strike is centered in Michigan is also critical. Mr. Biden won the state over former President Donald J. Trump with just over 50 percent of the vote. Without the state’s 16 electoral votes, Mr. Biden would not have defeated his rival.

Still, the president is unwavering on policies toward both unions and the environment. In a Labor Day speech in Philadelphia, Mr. Biden renewed both his vision about what he called a “transition to an electric vehicle future made in America” — which he said will protect jobs — and his rock-solid belief in unions.

“You know, there are a lot of politicians in this country who don’t know how to say the word ‘union,’” he said. “They talk about labor, but they don’t say ‘union.’ It’s ‘union.’ I’m one of the — I’m proud to say ‘union.’ I’m proud to be the most pro-union president.”