The United Auto Workers announced its endorsement of President Biden on Wednesday, a key, if expected, show of support as the president hones in on the general election.

The endorsement of the 400,000-member union is critical for Mr. Biden as he seeks to bolster his support among working class Americans. Mr. Biden became the first president in modern history to join a picket line when he visited striking workers near Detroit in September, a move UAW President Shawn Fain touted as he made the case to members that Mr. Biden, not former President Donald Trump, is their champion.

"Joe Biden bet on the American worker while Donald Trump blamed the American worker," Fain said in his announcement during the UAW's political convention in Washington, D.C. "We need to know who's gonna sit in the most powerful seat in the world and help us win as a united working class. So if our endorsements must be earned, Joe Biden has earned it ... UAW is endorsing Joe Biden for president of the United States!"

CBS News confirmed the endorsement before it was announced, and NBC News was the first to report it.

On Wednesday, Fain sought to contrast Trump with Mr. Biden, saying, "rarely as a union do you get so clear of a choice between two candidates." 

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

Blue-collar workers in union-heavy swing states such as Wisconsin and Michigan are critical for Mr. Biden's reelection bid as he seeks to fend off Trump, who is the front-runner for the Republican presidential nomination. Mr. Biden frequently refers to himself as the "most pro-union president in history," and cites his family's working class background and his childhood in Scranton, Pennsylvania, and then Delaware.

The UAW held off on endorsing Mr. Biden's reelection efforts for months, citing concerns that his administration's policies were too pro-electric vehicle. And Trump has garnered strong support from blue-collar workers, undoubtedly a continued concern for the Biden campaign. Fain sought to appeal to UAW members who might lean toward Trump. 

"Elections aren't about just picking your best friend for the job or the candidate who makes you feel good," Fain said Wednesday. "Elections are about power."

In September, Mr. Biden rallied alongside UAW workers in Michigan as they demanded better wages and benefits. The president took up a microphone and urged workers to "stick with it" in their fight for a "significant" raise.

"The fact of the matter is that you guys, the UAW, you saved the auto industry back in 2008 and before," Mr. Biden said outside a General Motors distribution center near Detroit. "Made a lot of sacrifices. Gave up a lot and companies were in trouble. But now they're doing incredibly well. And guess what? You should be doing incredibly well, too." 

On Wednesday, Fain sought to contrast Mr. Biden's approach with Trump's, pointing out that when Trump visited the Detroit area during the strike, the former president visited a non-union plant.

"Instead of talking trash about our union, Joe Biden stood with us," Fain said.

In the end, UAW workers and the big three automakers ratified a contract that significantly boosted wages and other benefits. 

During the last election, the UAW endorsed Mr. Biden in April 2020.

In:
• United Auto Workers

Kathryn Watson

Kathryn Watson is a politics reporter for CBS News Digital based in Washington, D.C.