FIRST ON FOX: Hunter Biden ripped former President Obama's chief strategist David Axelrod as a "giant a-- hole" in a 2015 email exchange with his longtime business partner Eric Schwerin and then-Vice President Biden's deputy counsel Alexander Mackler for allegedly telling Joe Biden not to run for president in 2016.

In the September 13, 2015, email exchange obtained by Fox News Digital, Mackler shared an Axelrod tweet with Hunter Biden and Schwerin. The tweet said that the 2016 election was "still [Hillary Clinton's] to lose, despite new polls."

"It's still HRC's to lose, despite new polls. But it's hard to inspire w/grinding, tactical race. ‘Hillary: Live With It’ is no rallying cry!" Axelrod tweeted.

"At the risk of being told for the second time this week that I need therapy…" Mackler said in response to the tweet. "This guy can take a flying leap. Cannot wait till he comes back to [Joe Biden] in a couple months and tells him it's time to run, after being the patronizing, self-appointed kingmaker earlier this year and telling him not to run (and then talking about the meeting all over TV)."

"He is a giant a-- hole," Hunter replied.

HUNTER BIDEN RIPPED BILL CLINTON AS ‘A--HOLE’ WHO ‘LOOKS LIKE S---,' SAID CLINTON AIDES ARE 'GREEDY': EMAILS

Hunter Biden

Hunter Biden speaks to guests during the White House Easter Egg Roll on April 18, 2022, in Washington. (AP Photo/Andrew Harnik)

The email exchange occurred a little over a month before Biden announced that the window for a potential presidential campaign announcement had "closed."

"Unfortunately, I believe we're out of time, the time necessary to mount a winning campaign for the nomination," Biden said during October 2015 remarks at the White House Rose Garden. "But while I will not be a candidate, I will not be silent."

In a 2017 email exchange less than two years later, Schwerin and Mackler took more shots at Axelrod over his backing of Clinton over Biden in response to a Washington Free Beacon article with the headline, "Axelrod Rips Clinton for Election Excuses: ‘It Takes a Lot of Work to Lose to Donald Trump’"

"Do you think he should have thought about this before he backed her to the exclusion of others?!?" Schwerin said, appearing to reference Biden as one of the "others."

"I'm old enough to remember when he took a whole afternoon of [Joe Biden's] time in the West Wing, arguing that he needed to get out of [Hillary Clinton's] way because she was the better candidate and would win," Mackler said.

David Axelrod

David Axelrod questions Democratic presidential candidate Pete Buttigieg during an event at the University of Chicago on Oct. 18, 2019. (Scott Olson/Getty Images)

Axelrod, a senior political commentator at CNN and the director of the University of Chicago's Institute of Politics, expressed "100 percent" support for Hillary Clinton as early as January 2015 during a phone call with top Clinton aide Huma Abedin, according to an email Abedin sent to other Clinton operatives. However, reports from 2016 regarding the Wikileaks emails show that Clinton staffers were concerned about Axelrod's criticism of Clinton and one aide even called his negative comments a "headache."

This isn't the first time that Hunter, Mackler, and Schwerin have attacked one of their fellow Democrats in emails. Fox News Digital reported last week that the trio took shots at Bill Clinton, Hillary Clinton's campaign, and a couple of her top aides.

The day after Bill Clinton appeared to blame Joe Biden in 2015 for the tougher sentencing provisions in the 1994 crime bill, Schwerin sent the clip to Hunter and Mackler, prompting Hunter to call him "an a--hole."

The day after Bill Clinton appeared to blame Joe Biden for the tougher sentencing provisions in the 1994 crime bill, Schwerin sent the clip to Hunter Biden and Mackler.

 "And God he looks like s---," Hunter added.

Bill Hillary Clinton

Former President Bill Clinton and former Secretary of State Hillary Clinton arrive for the 59th presidential inauguration at the U.S. Capitol on Jan. 20, 2021. (AP Photo/Carolyn Kaster)

In another email exchange in late 2015, Hunter Biden and Mackler continued to take shots at a close Hillary Clinton aide, responding to a Washington Post article Schwerin shared with the headline, "While at State, Clinton chief of staff held job negotiating with Abu Dhabi," referring to Cheryl Mills.

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"For f---'s sake. This is incredible. It never ends," Mackler said.

 "Truly absurd. If this is acceptable then would it also have been acceptable for Ron Klain to remain general counsel of Revolution while acting as COS for the VP?" Hunter asked.

Axelrod, Hunter's attorney, and Mackler did not respond to Fox News Digital's requests for comment.

Fox News' Jessica Chasmar contributed to this report.