Over 60 conservative leaders are coming to the defense of embattled White House acting Chief of Staff Mick Mulvaney, who has faced rumors he could be on the way out of the Trump administration.

After a widely panned press conference last Thursday and an attempt to smooth things over on "Fox News Sunday," a group called the Conservative Action Project is sending a letter to White House and congressional leaders imploring them to stand with Mulvaney and keep him in the administration.

"Conservatives are proud to support the role Mick Mulvaney continues to play in the Trump Administration," the letter, obtained by Fox News and signed by dozens of prominent conservatives, reads. "Recent news reports demonstrate that ... the D.C. Swamp is attacking him—and we believe it is because he has been the most successful Chief of Staff in this administration to advance the Trump pro-America agenda."

MULVANEY INSISTS NO QUID PRO QUO WITH UKRAINE AFTER WH COMMENTS: 'I DIDN'T SAY THAT'

Mulvaney seemed to contradict President Trump’s claim there was no “quid pro quo” during his controversial July 25 phone call with Ukrainian leader Volodymyr Zelensky, by telling reporters at the press conference that the release of military aid to Ukraine was tied to the administration’s demands that Kiev investigate controversies involving Democrats during the 2016 campaign.

"Did [Trump] also mention to me, in the past, the corruption related to the DNC server? Absolutely," Mulvaney said in the press conference. "No question about that. But that’s it. And that’s why we held up the money ... The look back to what happened in 2016 certainly was part of the thing that he was worried about in corruption with that nation. And that is absolutely appropriate.”

Mulvaney later walked back his statement, including on "Fox News Sunday," an interview one Trump ally described to Politico as "self-immolation."

The signatories of the letter, titled "Memo for the Movement," include the heads of high-profile conservative organizations such as Heritage Action for America, the Tea Party Patriots Citizen Fund, March for Life Action and the Family Research Council. The letter focuses on Mulvaney's track record of working with the Trump administration on issues such as tax cuts, regulatory reform and energy policy.

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"As director of the Office of Management and Budget and as acting White House Chief of Staff, Mulvaney has overseen the office most responsible for implementing the Trump agenda throughout the government," the letter says. "His attention, vision, and commitment to the president's policies has been evident from the beginning of the Administration to today. We believe the president should make him permanent in the Chief of Staff role."

Fox News' Joshua Nelson contributed to this report.