United Auto Workers Union President Shawn Fain had some tough words for former President Donald Trump on Wednesday.

“Donald Trump is a scab!” the labor leader yelled in a speech to members in Washington, thumping his finger on the podium for emphasis.

The insult was one of many Fain tossed at Trump as he announced the union’s endorsement of President Joe Biden for reelection.

Fain cast Biden as a steadfast ally to unions and the working-class — and Trump as the opposite. He said the former president was a friend to the “billionaire class” and sought to undermine workers at the benefit of the rich.

“Donald Trump is a billionaire and that’s who he represents,” Fain said. “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.”

He pointed out that Biden publicly stood with the UAW members during their recent strike against Ford, General Motors and Jeep parent company Stellantis, when he visited a Michigan picket line in September.

Trump, on the other hand, had the opportunity to publicly support striking GM workers when he was president in 2019, but he declined to do so, Fain said.

“He said nothing, he did nothing – not a damn thing, because he doesn’t care about the American worker,” Fain said.

Instead, Trump opted to visit a non-union auto parts plant to deliver a speech during the strike.

“Instead of talking trash about our union, Joe Biden stood with us and supported our historic victory,” Fain said. “Rarely as a union do you get so clearly a choice between two candidates.”

Although Trump has not locked up the GOP nomination yet, his only challenger left is former South Carolina Gov. Nikki Haley. Trump prevailed in the New Hampshire primary on Tuesday, leading 54% to Haley’s 43% as of Wednesday afternoon.