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

The head of the International Association of Fire Fighters (IAFF) called President TrumpDonald John TrumpNational Archives says it altered Trump signs, other messages in Women's March photo Dems plan marathon prep for Senate trial, wary of Trump trying to 'game' the process Democratic lawmaker dismisses GOP lawsuit threat: 'Take your letter and shove it' MORE’s attacks over the organization’s endorsement of former Vice President Joe BidenJoe BidenSanders to headline Iowa event amid impeachment trial Hillicon Valley: Biden calls for revoking tech legal shield | DHS chief 'fully expects' Russia to try to interfere in 2020 | Smaller companies testify against Big Tech 'monopoly power' Hill.TV's Krystal Ball on Sanders-Warren feud: 'Don't play to the pundits, play to voters' 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 GillibrandSanders defends vote against USMCA: 'Not a single damn mention' of climate change The Hill's Morning Report — President Trump on trial Overnight Energy: Schumer votes against USMCA, citing climate impact | Republicans offer details on their environmental proposals | Microsoft aims to be carbon negative by 2030 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