Lev Parnas, an associate of President Trump's personal attorney Rudy Giuliani, said Thursday night that Mr. Trump tried to fire former U.S. Ambassador to Ukraine Marie Yovanovitch "at least four or five times" before she was eventually removed from her post.

"The president kept firing her, and she wouldn't leave," Parnas told MSNBC's Rachel Maddow.

Parnas described one of those attempts in detail. He told Maddow that on April 30, 2018, he dined with Mr. Trump, Donald Trump Jr., and three other people in a private section of the Trump Hotel.

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At the dinner, he alleged, he told Mr. Trump that Yovanovitch had been bad-mouthing him and saying he would be impeached.

"And at that point, he turned around to John DeStefano, an aide at the time, and said, 'Fire her,'" Parnas said. "And we all — there was a silence in the room. And he responded to him and said, 'Mr. President, we can't do that right now because Pompeo hasn't been confirmed yet.'"

Parnas loosely described other instances in which Mr. Trump allegedly tried to fire Yovanovitch, including one in which he allegedly had a "breakdown" and yelled at his assistant, Madeleine Westerhout, to do it for him.

He claimed both Pompeo and former national security adviser John Bolton would not let Mr. Trump fire her.

"He fired her when he gave an order to Mike Pompeo once which he didn't do — Secretary Pompeo didn't fire her," he said. "Then Rudy came back and he told him, go speak to Pompeo. Rudy went to speak to Pompeo. They got into it. Then they had another meeting at the White House where he told Bolton to fire her. Bolton didn't want to fire her." He did not provide any concrete evidence backing these allegations.

Yovanovitch was not recalled to Washington until more than a year after the alleged dinner, in May 2019. Maddow said that the State Department did not respond to a request for comment.

In response to the first half of Parnas' interview, which aired Wednesday night, White House press secretary Stephanie Grisham called Parnas "a man who is currently out on bail for federal crimes and is desperate to reduce his exposure to prison."

"The facts haven't changed — the president did nothing wrong and this impeachment, which was manufactured and carried out by the Democrats has been a sham from the start," she added.

Parnas, 47, and his associate Igor Fruman are accused of helping Giuliani attempt to investigate former Vice President Joe Biden and his son Hunter in Ukraine. Parnas, a Ukrainian-born U.S. citizen, and Fruman, originally from Belarus, were arrested on campaign finance charges at Virginia's Dulles International Airport in October.

Parnas also alleged during the interview that Mr. Trump's attorney, Jay Sekulow, was "absolutely" aware of his and Giuliani's efforts in Ukraine.

"Everybody was in the loop," he said, adding that Sekulow disapproved of the efforts and "wanted to stay away" from what was happening. Parnas did not provide concrete evidence showing that Sekulow was aware of the extent of Giuliani's efforts in Ukraine, although he said he heard the pair discussing it.

Parnas also implicated two of Mr. Trump's other lawyers, Kevin Downing and John Dowd. He told Maddow he called Giuliani once Congress sought his cooperation with the impeachment inquiry, and Giuliani connected him with Dowd.

Dowd originally said he would represent him, Parnas said, but called back 15 minutes later to say that Sekulow had told him it would be a conflict of interest to work with both Parnas and Mr. Trump.

"He goes, 'I've been speaking with Jay Sekulow and because I was the president's attorney and I'm still kind of doing work for the president, uh there's a conflict of interest unless he wants to waive, and I don't think the president's going to waive that conflict,'" Parnas recalled.

Parnas said he insisted the president would approve it, and directed Dowd to check with Mr. Trump.

"About 15, 20 minutes later, I got a call back from John Dowd," he said. "He said, 'Uh you're one lucky guy. I just got a call from Jay Sekulow. I got the permission. And I'm getting it in writing shortly.'"

The partnership was short-lived, however, as Parnas fired Dowd and Downing once he was arrested. He told Maddow the trio had a heated jailhouse confrontation in which he felt the lawyers were trying to convince him to take the fall for Mr. Trump.

"I called Downing to come there. And I started seeing in the process of the bail stuff, the way things were going on ... I didn't feel that they were trying to get me out," Parnas said, adding "John Dowd instead of comforting me and trying to calm me down and telling me 'it's going to be OK, don't worry,' he started talking to me like a drill sergeant."

He said Dowd's general message was, "Be a good boy," although he acknowledged he didn't remember the exact words.

When asked if he felt pressured "to sacrifice yourself to protect Trump," Parnas said, "That's the way I felt."

"They tried to keep me quiet," he added.

Dowd contested Parnas' claims in a statement to CBS News on Friday. "In jail, Parnas said he was getting new counsel," he said. "[Myself and Kevin Downing] left and Parnas announced he had no money for bail. No one instructed Parnas to sacrifice for POTUS."

—Catherine Herridge contributed reporting.