President Trump and Democratic presidential candidate Joe Biden traded barbs on Monday after a firefighters' union endorsed Biden, becoming the first major labor group to back a candidate in the 2020 race.
The International Association of Fire Fighters announced its decision in a video message that described Biden as an advocate for the middle class.
"Joe's a lot like our firefighters. He's a problem solver who cares deeply about America and committed to making our country better. He's one of the staunchest advocates for working families," said Harold Schaitberger, the IAFF's general president. "He knows that a strong middle class means a strong America, and we know, as president, he will stand up for all the patriotic Americans who want nothing more than to earn a decent wage, send their kids to college, have affordable health care and a decent and secure retirement."
Biden said on Twitter that he "couldn't be more proud" to have the union's backing. "Unions built the middle class in this country - and as President, I'll fight to strengthen them and grow the backbone of this country," he wrote.
Later Monday, Trump attacked Biden and the IAFF on Twitter, accusing the union of charging exorbitant dues and claiming that its members would rather support him than Biden.
Biden responded by tweeting that he is "sick" of Trump "badmouthing unions."
Biden has long had the support of organized labor and has strong ties to unions. He is formally launching his campaign Monday with a rally in Pittsburgh at the union hall of Teamsters Local 249.