US PRESIDENT JOE Biden has joined the United Auto Workers on the 12th day of their strike against major car makers, a demonstration of support apparently unparalleled in American history.

Biden’s embrace of the union began as soon as he arrived in Michigan on Air Force One.

UAW president Shawn Fain was the first to greet Biden on the tarmac and he joined him in the presidential limousine for a ride to the picket line.

They soon arrived at a General Motors parts distribution warehouse located in the suburbs west of Detroit, one of the facilities that has been targeted in the strike.

“No deal, no wheels,” workers chanted. “No pay, no parts.”

Labour historians say they cannot recall an instance when a sitting president has joined an ongoing strike, even during the tenures of the more ardent pro-union presidents such as Franklin Delano Roosevelt and Harry Truman.

Theodore Roosevelt invited labour leaders alongside mine operators to the White House amid a historic coal strike in 1902, a decision that was seen at the time as a rare embrace of unions as Roosevelt tried to resolve the dispute.

Biden will be arriving one day before former president Donald Trump, the front-runner for the 2024 Republican nomination, goes to Detroit to hold his own event in an attempt to woo car workers – even though union leaders say he is no ally.

Lawmakers often appear at strikes to show solidarity with unions and Biden joined picket lines with casino workers in Las Vegas and auto workers in Kansas City while seeking the 2020 Democratic presidential nomination.

Sitting presidents, though, have to balance the rights of workers with disruptions to the economy, supply chains and other facets of everyday life, have long wanted to stay out of the strike fray, until Biden.

“This is absolutely unprecedented. No president has ever walked a picket line before,” said Erik Loomis, a professor at the University of Rhode Island and an expert on US labour history.

Presidents historically “avoided direct participation in strikes. They saw themselves more as mediators. They did not see it as their place to directly intervene in a strike or in labor action”.

White House press secretary Karine Jean-Pierre told reporters aboard Air Force One en route to Michigan that “Biden is fighting to ensure that the cars of the future will be built in America by unionised American workers in good-paying jobs, instead of being built in China”.