Biden needles Trump over his hair and 'Mar-a-Lago values' as he addresses union

President Joe Biden on Wednesday needled rival Donald Trump, laying into the former president as he welcomed the North America's Building Trades Union's endorsement.

"You're the best in the world," Biden said while addressing the NABTU's legislative conference in Washington, D.C. "You know, you had my back in 2020 and because of you, I'm standing here as president of the United States of America. … Because of you, in 2024 we're going to make Donald Trump a loser again! Are you ready?"

"So, it's either Scranton values or Mar-a-Lago values," Biden went on to say, drawing a contrast between his background and Trump's as he repeated an economic argument rolled out during campaign stops in Pennsylvania last week. "These are competing visions of the economy at the heart of this election."

Polling shows that economic issues are top of mind for many voters in what is expected to be a close race, though surveys have found Trump getting more favorable marks than Biden on the economy.

The president doubled down on his differences with Trump later in his speech on Wednesday and said working-class voters are probably familiar with the kind of elites that Biden argued Trump represents.

"Folks, the choice is clear: Donald Trump's vision of America is one of revenge and retribution, a defeated former president who sees the world from Mar-a-Lago and bows down to billionaires, who looks down on American union workers," Biden said.

"Think about the guys you grew up with [that] you'd like to get into the corner and just give them a straight left," Biden said. "I'm not suggesting we hit the president."

Biden -- who has been hammered by Trump and Republicans over high inflation and cost of living issues -- said Trump repeatedly promised to focus on so-called infrastructure week when he was president but in four years "he never built a damn thing," compared with the Biden White House's successful push for new infrastructure investment.

Biden also slammed his predecessor for Trump's alleged treatment, as a businessman, of contractors: "He didn't keep his word."

"The guy has never worked a day in working man's boots," he said of Trump.

Biden also sarcastically took shots at Trump's history of outlandish comments -- reversing a frequent attack from Trump on Biden's own well-known habit of verbal gaffes and misstatements.

"Donald Trump still thinks windmills cause cancer," Biden said to laughter as he made the sign of the cross. "That's what he said. And by the way, remember when he was trying to deal with COVID, he suggested just inject a little bleach in your veins? He missed it -- it all went to his hair. Look, I shouldn't have said that."

During one other moment, however, Biden apparently read aloud a stage direction to "pause" during his speech, presumably for applause. It was a familiar slip for the president, who looked momentarily confused while reading it before giving a large smile when he seemingly realized his mistake.

In the audience, many members wore T-shirts that read "Joe walks the line," with a depiction of the president wearing his signature aviator sunglasses.

NABTU President Sean McGarvey praised Biden in a statement on Wednesday announcing the union's endorsement, which adds to the list of labor groups backing Biden.

NABTU also endorsed Biden over Trump in the 2020 election. Trump has been supported by some other high-profile unions, including those representing Border Patrol agents and police.

"Joe Biden has proven to be the perfect leader at the perfect time for this country and the working men and women who have built it," McGarvey said in his statement.

He said NABTU, a coalition of unions that boasts 3 million members, plans to mobilize its members to vote for Biden in the fall.