Firefighter union leader calls Trump attacks over Biden endorsement 'counterproductive' 

The head of the International Association of Fire Fighters (IAFF) called President TrumpDonald John TrumpPompeo changes staff for Russia meeting after concerns raised about top negotiator's ties: report House unravels with rise of 'Les Enfants Terrible' Ben Carson: Trump is not a racist and his comments were not racist MORE’s attacks over the organization’s endorsement of former Vice President Joe BidenJoe BidenHouse unravels with rise of 'Les Enfants Terrible' Sanders to call on 2020 Democrats to reject money from drug, health insurance industries Harris tops Biden in California 2020 poll MORE in the 2020 Democratic primary “counterproductive.”

Harold Schaitberger told Hill.TV on Thursday that Trump has a lot of “audacity” to claim last month that he has “done more for Firefighters than this dues sucking union will ever do."

“I didn’t find that helpful and quite frankly I think it was counterproductive,” Schaitberger said.

The union leader added that despite the backlash, the IAFF hasn’t lost “any membership” over its endorsement. He estimated that out of 316,000 members across the country, 602 reached out to the union to criticize the move.

“One thing about firefighters, even when we disagree, we come together,” he told Hill.TV. “We don’t like anybody attacking our family from the outside … whether that’s on the job or in the political arena.”

Schaitberger said the union continues to be “all in” for Biden’s campaign for president. He emphasized that the organization plans to be very active throughout the Democratic primary and has already started planning for its early primary caucus and state operations.

“I’m very confident we’ll be successful and Joe will become the nominee and the next president,” he told Hill.TV.

Since the launch of his president campaign in April, Biden has touted his close ties to labor unions. He kicked off his official White House bid by hosting a union event in Pittsburgh.

"I make no apologies. I am a union man. Period," Biden told the crowd.

A number of other 2020 Democratic candidates are also aiming to win the support of unions. 

Last month, a handful of 2020 hopefuls, including former Housing and Urban Development Secretary Julián Castro and Sen. Kirsten GillibrandKirsten Elizabeth GillibrandThe Hill's 12:30 Report: Trump digs in ahead of House vote to condemn tweet 'Game of Thrones' scores record-breaking 32 Emmy nominations The Hill's Morning Report - Presented by JUUL Labs - House to vote to condemn Trump tweet MORE (D-N.Y.), joined striking McDonald’s workers to express solidarity with their fight over better wages.

“I’m going to join workers anywhere they're fighting for a living wage and safe working conditions,” Castro tweeted along with a video of him marching alongside workers in North Carolina. 

 —Tess Bonn