President Donald Trump went on a retweeting spree early Wednesday, promoting tweets from nearly 60 accounts that replied to a post regarding the International Association of Firefighter's support for former Vice President Joe Biden in the 2020 presidential race.

Trump retweeted 59 replies to conservative media personality Dan Bongino's tweet within a span of 20 minutes, promoting tweets from users who claimed firefighters did not support Biden.

The binge began after Trump promoted Bongino's initial tweet, claiming that the firemen he knew were not supporting Biden.

"I’ve done more for Firefighters than this dues sucking union will ever do, and I get paid ZERO!" Trump wrote. On Monday, ahead of Biden's first campaign rally in Pittsburgh, Trump also criticized "dues sucking" union leadership that "will always support Democrats, even though the membership wants me."

A sampling of Trump's retweets Wednesday morning:

Joe Biden is not even his party’s candidate yet. Firemen 🚒 can’t say they endorse him. He may not even be on ballot. Real firemen support President Trump. 🇺🇸🇺🇸🇺🇸 — 🇺🇸TarHeel🐏 (@flamingoHeels) May 1, 2019

Just the union leadership supports Biden. Members support Trump. This applies to most unions. — Jeffrey Stewart (@JeffreyKStewart) April 30, 2019

This firefighter won’t be voting for creepy @JoeBiden — Curtis Vincent (@CurtisVincent5) April 30, 2019

Soon after being retweeted by Trump, one apparent supporter changed their username to "F---Donald Trump." That tweet was not immediately deleted from Trump's account.

Later Wednesday, Biden responded to Trump's tweet storm.

"I understand the president's been tweeting a lot about me," Biden said during a campaign stop in Iowa City, Iowa. "I wonder why the hell he's doing that? Anyway, imagine I'm going to be the object of his attention for a while."

On MSNBC Tuesday, Harold Schaitberger, the president of the IAFF, said Biden "will actually speak to those voters, be able to connect with those voters that left because he’s had a 40-year career delivering for them."

Before the union endorsed Biden, it polled Democratic, independent and non-party-identified members, who make up more than 180,000 of its 316,000 members, and they "came out overwhelmingly for Joe," Schaitberger told NBC News on Monday.

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The poll of 1,500 respondents was conducted by Zogby Strategies in mid-April, he said, adding that it did not include Republican union members because it was focused on helping come to a decision about which Democratic nominee to endorse.

The union declined to release the results of the poll. It did not endorse Democratic presidential nominee Hillary Clinton in 2016.

Trump has tweeted multiple times on Biden within the past week as the former vice president announced the launch of his campaign. In an announcement video, Biden targeted Trump's response to the 2017 white nationalist rally in Charlottesville and said in his opening rally that his candidacy will be about "truth over lies."

Since announcing last week, Biden has surged in early polling, opening up a sizable lead over his Democratic competition.