WASHINGTON − President Joe Biden had just landed in Philadelphia, where he would later hail the virtues of unions in a speech on Labor Day, when he downplayed the possibility autoworkers could strike at the nation's three largest automobile manufacturers.

“No, I’m not worried about a strike until it happens," Biden told reporters this month. "I don’t think it’s going to happen.”

Two weeks later, the historic strike from United Auto Workers at Stellantis, Ford and General Motors plants did happen and Biden changed his tone dramatically: from being "not worried" about a potential walkout to standing firmly behind UAW's demands, making it unmistakable whose side he is on in the tense standoff.

It marked the most forceful public backing of a negotiating party that Biden − who has said he wants to be known as "the most pro-union president" in U.S. history − has taken in a private labor dispute since entering the White House.

And it comes as Biden is leaning into his pro-union credentials as he pushes a working-class message in the 2024 election in hopes of again winning the critical Rust Belt states of Michigan, Pennsylvania and Wisconsin.

"No one wants a strike. But I respect the workers' right to use their options under the collective bargaining system. And I understand the workers' frustration," Biden said in remarks from the White House on Friday, adding that workers deserve a "fair share" from the automakers.

"Record corporate profits, which they have, should be shared by record contracts for the UAW," Biden said.

Biden needs union workers in Michigan, other Midwest states

The UAW strike has collided directly with the 2024 election.

A key factor in Biden repeating wins in Michigan, Pennsylvania and Wisconsin is whether he can hold the line on support from rank-and-file union members who defected from the Democratic Party in the past two election cycles to vote for Donald Trump, the Republican frontrunner again in 2024.

Despite having the endorsements of UAW and other labor unions in the 2020 election, Biden won the support of about six in 10 union members, according to the Associated Press' Vote Cast, a sizeable but not overwhelming margin.

"It's politically smart for him to be 100% behind the UAW, but it's also what he truly believes," said David Cohen, a professor of political science at the University of Akron. "It's really the only position he can take, to be honest."

Biden faced additional pressure to voice support for the UAW because his strong embrace of electric vehicles as part of his climate agenda has caused friction with union allies.

The manufacturing of electric vehicles typically requires fewer workers. Biden has made clear he wants the transition to electric vehicles to create "good-paying union jobs." But UAW's new leadership, led by President Shawn Fain, was furious after the Department of Energy in June awarded a $9.2 billion grant to Ford and a South Korean battery maker that lacked assurances for workers.

"We expect action, not words," Fain told CBS' Face the Nation on Sunday when asked about the UAWs decision to hold off endorsements in the 2024 election. He said the UAW's endorsement must be "earned."

Fain, in a statement after Biden's White House speech, said, "We agree with Joe Biden when he says 'record profits mean record contracts.' We don’t agree when he says negotiations have broken down. Our national elected negotiators and UAW leadership are hard at work at the bargaining table."

He accused the auto companies and media of using "fear tactics" to suggest striking autoworkers will wreck the economy.

"We’re not going to wreck the economy. The truth is we are going to wreck the billionaire economy.Working people are not afraid. You know who’s afraid? The corporate media is afraid. The White House is afraid. The companies are afraid," Fain said.

Biden campaign fires back at Trump's plans to visit Detroit

The UAW's strike began at midnight Friday when nearly 13,000 workers walked out of Ford Michigan Assembly Plant in Wayne, Michigan, Stellantis Toledo Assembly Complex in Ohio and GM's Wentzville Assembly in Missouri. If the union and the automakers can't reach a tentative agreement, at some point the UAW has said it plans to strike more plants across the three companies.

Workers are seeking a 40% pay raise, a four-day workweek, the elimination of a multi-tiered wage system and the restoration of a 1980s-style pension plan, among other demands.

Several Democratic lawmakers, including House Democratic Leader Hakeem Jefferies and Sen John Fetterman, D-Pa., as well as progressive independent Sen. Bernie Sanders of Vermont have traveled to Michigan to join autoworkers at the picket lines.

Trump, who has argued Biden's support of electric vehicles has put autoworkers' career at risk, will visit the Detroit area on Sept. 27 rather than take part in the second GOP primary presidential debate.

"The United Autoworkers are being sold down the 'drain' with this all Electric Car SCAM," Trump said on the Truth Social media site.

The Biden campaign is working aggressively to counter those punches.

The campaign and Democrat allies pointed to the Trump administration's "unfriendly policies" toward unions, 2017 tax cuts for corporations, and past comments questioning the federal government's 2008 bailout of the auto industry under President Barack Obama.

"While President Trump's going to come in and try to erase his history with Michigan workers next week, I think that Michiganders are going to know what the record was and will reject his anti-worker agenda," said U.S. Rep. Debbie Dingell, D-Michigan, a Biden ally.

Prior to the 2016 election, Dingell correctly predicted Trump could carry Michigan.

"I said it because I was in those union halls. And Donald Trump has one skill - a skill that Democrats have as well - which is to understand people's concerns and their anxieties," Dingell said, adding that Democrats did not do a good enough job counter Trump's focus on trade policy in 2016. "We will not make that mistake again."

Some Democrats have urged Biden to join strikers at the picket-line, but the White House has given no indication the president will take such an unprecedented step.

Meanwhile, Fain urged fellow UAW members to reject Trump's overtures.

"Every fiber of our union is being poured into fighting the billionaire class and an economy that enriches people like Donald Trump at the expense of workers," Fain said in a statement Tuesday. "We can’t keep electing billionaires and millionaires that don’t have any understanding what it is like to live paycheck to paycheck and struggle to get by and expecting them to solve the problems of the working class.”

White House staying out of negotiations

For now, the White House is keeping negotiations between UAW and the autoworkers at an arms length. Acting Labor Department Secretary Julie Su and White House adviser Gene Sperling are heading to Detroit this week, but not to act as mediators but rather to offer support if requested by the parties.

That's in stark contrast to when Biden intervened directly while rail workers threatened a strike that would have crippled freight deliveries. Unlike the autoworkers' strike, the federal government plays a unique role to set contracts in rail disputes.

In April, Biden voiced support for Amazon workers' right to unionize. The White House has said all workers, including actors, should be paid fairly in response to the strike from the Writers Guild of America. But Biden's comments about UAW's strike went beyond either of those situations.

The White House contends that Biden's support for UAW strikers is in line with statements he made leading up to the strike.

Biden, in an Aug. 14 statement, said "UAW deserves a contract that sustains the middle class." Later, on Sept. 1, Biden lauded federal funding that "will help existing workers keep their jobs" after the federal government made $12 billion available to help companies ease the transition to electric vehicles. UAW also praised the funding.

"Just as we’re building an economy of the future, we need labor agreements for the future," Biden said Friday. "It’s my hope that the parties can return to the negotiation table to forge a win-win agreement."

Reach Joey Garrison on X, formerly known as Twitter, @joeygarrison.