President Biden took aim at former President Trump at a campaign event in Pennsylvania on Saturday, using his remarks to cast his predecessor as an anti-labor leader who, if reelected, would renege on some of the union's hardest-fought gains.

Speaking at an event in Pittsburgh, Biden repeatedly described Trump as a "loser" who doesn’t care about union workers and would gladly do away with benefits like health care and pension plans if he won the presidency for a second time.

"Donald Trump is a loser," Biden told the audience. "He’s a loser of a candidate – and he’s a loser of a man." 

"I’ve never been this direct," Biden added. "But I tell you what, [Trump] is about making sure you push people down. He thinks the way you get ahead is to push people down." 

His remarks were tailored specifically to union workers in Philadelphia, a group that has until recently been a reliable bedrock of support  for Democratic candidates. But labor politics have shifted in recent years, especially in Rust Belt states to favor Trump – with many workers citing his accessible rhetoric and appeal to working-class voters.

Some longtime unions have altogether declined to endorse a presidential candidate in 2024, citing the split ideology among their membership.

Many also remain lukewarm about Harris’s campaign, viewing her as having done too little to win their vote in the months since entering the presidential race.

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Biden’s speech Saturday attempted to rectify that – even as most of his remarks were focused on criticizing the former president, whom he noted has tried "51 times" to eliminate health care coverage for union employees.

"The last thing we need is for Trump to get elected, to take away all the things we've done," he said. "How many of you have pensions now? How many of your families have pensions?" Biden asked.

Trump, he said, "opposes it."

He also made an indirect swipe at Tesla founder and Trump ally Elon Musk, criticizing an unnamed "illegal worker" that has used his funds and public persona to stump on behalf of the former president. 

"Turns out the wealthiest man in the world, now [Trump’s] ally, was an illegal worker here," Biden told the audience, though he stopped short of mentioning Musk by name. 

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The Biden administration did not immediately respond to a request from Fox News Digital for clarification about the president's remark. 

Musk is one of Trump’s highest-profile supporters, and to date has donated more than $118 million to a super PAC supporting his reelection.

The unsparing criticism in the speech was something new from Biden, now a lame-duck candidate in his final two months of the presidency. 

And that knowledge may have invigorated the outgoing president, whose voice got louder and stronger as his speech continued.

"There is more to do, and Kamala is going to make it happen," Biden said, imploring the crowd once again to vote in the Nov. 5 election.

"I can think of no man who has thought less of the American worker," Biden said of Trump. He is a man with "no character," and who "doesn't give a d--- about union members."