United Auto Workers endorse Biden; union president calls Trump a 'scab'

President Joe Biden received a key 2024 endorsement on Wednesday from the United Auto Workers, with the union's president using the occasion to savage Biden's likely general election opponent, Donald Trump.

Shawn Fain announced UAW's support for Biden's reelection bid at their biannual conference in Washington, D.C.

"I know there's some people that want to ignore this election," Fain said. "They don't want to have anything to do with politics. Other people want to argue endlessly about the latest headline or scandal or stupid quote. Elections aren't about just taking your best friend for the job or the candidate who makes you feel good. Elections are about power."

The backing of the Michigan-based UAW, with more than 400,000 members, could give Biden an edge in a key battleground state that has helped determine the last two political elections. He won Michigan by about 150,000 votes in 2020; Trump won it by about 10,000 votes four years earlier.

Biden also won the group’s endorsement in 2020, and it backed Hillary Clinton over Trump in 2016.

But Trump was successful in battlegrounds like Michigan and Ohio in that election cycle in part because of his ability to attract more union support than past GOP candidates: The UAW said at the time it believed one in four of its members likely voted for Trump based on surveys.

"The question is, who do we want in that office to give us the best shot of winning?" Fain said on Wednesday. "Who gives us the best shot of organizing? Who gives us the best shot of negotiating strong contracts? Who gives us the best shot of uniting the working class and winning our fair share once again?"

Biden, who has increasingly been gearing in public to face Trump in the general election, also delivered remarks. He thanked the union for its support and praised members for inspiring the labor movement with its strike last year against the Big Three auto makers.

"Let me just say, I'm honored to have your back and you have mine, that's the deal," Biden said. "It comes down to seeing the world the same way, it's not complicated."

Fain cast the 2024 race as a choice between Biden and Trump and didn't mince words in his criticism of the former president. He specifically took issue with Trump's handling of the union's 2019 strike, arguing that Trump didn't do a "damn thing" while UAW members confronted General Motors at plants across the U.S.

"Donald Trump is a scab," Fain said. "Donald Trump is a billionaire, and that's who he represents. If Donald Trump ever worked in auto plant, he wouldn't be a UAW member -- he'd be a company man trying to squeeze the American worker."

Trump's campaign did not immediately respond to a request for comment on Fain's remarks, though Trump has previously dismissed Biden's record on unions.

Last year, Biden joined UAW members striking in Michigan against General Motors, Ford and Stellantis on the picket line in a historic show of support for workers amid their contract negotiations with the auto giants for better wages and conditions.

"If our endorsements must be earned, Joe Biden has earned it," Fain said on Wednesday.

Biden, who has touted himself as the most "pro-union" president, told members that union workers are central to his economic vision to build the economy from the middle out and bottom up.

"Together, we're proving what I've always believed," Biden said. "Wall Street didn't build America, the middle class built America and unions built the middle class."

He continued, "As long as I’m president, the working people are gonna get their fair share. ... You deserve it."

Trump, too, visited Michigan last September just a day after Biden to try to woo auto workers and union members. He delivered a speech at a non-unionized plant.

In that speech, Trump repeated his pitch for economic nationalism, calling himself the only candidate who wants to protect American labor -- which was a key pledge in his previous campaigns.

He also attacked Biden for the federal government's environmental regulation push on tailpipe pollution, which would encourage more electric vehicle manufacturing -- while also raising the concerns of auto workers like those in the UAW. Biden has said he wants to invest in the auto industry to spur more electric vehicle use to address climate change.

Trump took a darker view.

"You're all on picket lines and everything, but it doesn't make a damn bit of difference what you get because in two years -- you're all going to be out of business," he said in September. "You're not getting anything. What they're doing to the auto industry in Michigan and throughout the country is absolutely horrible and ridiculous."

ABC News' Lalee Ibssa and Soo Rin Kim contributed to this report.