By Jeremy Herb and Erica Orden, CNN

(CNN) -- Geoffrey Berman, the former US attorney in Manhattan fired last month following a tense standoff with Attorney General William Barr, told a congressional panel Thursday that Barr had pressured him to resign and had warned he could be harming his future job prospects if he did not do so.

"The Attorney General said that if I did not resign from my position I would be fired. He added that getting fired from my job would not be good for my resume or future job prospects. I told him that while I did not want to get fired, I would not resign," Berman told the House Judiciary Committee in a closed-door interview, according to a copy of his opening statement obtained by CNN.

Berman said he objected to Barr's plans to appoint an acting US attorney for the Southern District of New York who was not in the office already. He testified that Barr's initial announcement that New Jersey US Attorney Craig Carpenito would become acting US attorney in Manhattan would have been "unprecedented, unnecessary and unexplained," according to his statement.

Berman is testifying on Capitol Hill in House Democrats' latest push to scrutinize what they charge is unprecedented politicization of the Justice Department.

Berman appeared behind closed doors before the House Judiciary Committee to discuss his dismissal as US attorney for the Southern District of New York, which has investigated a number of President Donald Trump's associates. Berman detailed his in-person meeting and follow-up phone call with Barr on June 19, when the attorney general told him he was being replaced because the chairman of the Securities and Exchange Commission, Jay Clayton, was being nominated to be the next US attorney in Manhattan.

Berman was fired the following day after refusing Barr's request for him to resign, sparking a chaotic and confusing 24 hours in the most powerful prosecutors' office outside Washington.

Barr's critics say Berman's firing, which Trump carried out at Barr's request, is only the latest in a series of moves the attorney general has made to aid the President. Democrats have criticized Barr on multiple fronts, including his handling of special counsel Robert Mueller's report, the dismissal of charges against Trump's first national security adviser Michael Flynn and his role in the forceful removal of peaceful protesters outside the White House.

Thursday's closed-door interview comes ahead of Barr's scheduled public testimony before the House Judiciary Committee later this month.

Last month, the panel held a public hearing where two current Justice Department prosecutors -- including a former member of Mueller's team -- accused Barr of politicizing the sentencing of Trump's longtime friend Roger Stone and meddling in antitrust investigations involving the cannabis industry. The committee has also lined up a witness who filed a whistleblower complaint with the Justice Department inspector general to testify about the handling of an investigation into Walmart and opioids.

Some Democrats have urged the House to begin impeachment proceedings against Barr, but Speaker Nancy Pelosi tamped down that talk last month, saying Democrats should instead "solve our problems by going to the polls."

Barr and Trump's Republican allies in Congress have dismissed allegations of politicization. Barr spokeswoman Kerri Kupec dismissed the calls for Barr's impeachment as "a political thing."

"If people have a problem with Bill Barr coming back to the Department of Justice to restore one system of justice, not a two-tiered system, I think that says a lot more about the critics than it does about the attorney general," Kupec said in an interview last month on "Fox and Friends."

Thursday's hearing is Berman's first public appearance since his abrupt and tumultuous departure.

Berman told the committee that Barr met with him at the Pierre hotel in Manhattan on June 19, telling him he planned to make a change atop the Southern District of New York and that Berman should take a job in the Justice Department leading the Civil Division. Over sandwiches that went untouched, Barr told Berman that he intended to nominate Clayton as his successor, and Berman replied that Clayton was an "unqualified choice for US attorney" because he was never an assistant US attorney and had no experience prosecuting criminal cases.

Berman said Barr urged him to resign but he refused.

"I responded that I loved my job and my colleagues at the Southern District and that I was thankful every day for the privilege of being part of that office," Berman said, according to his opening statement. "I asked the Attorney General if he was in any way dissatisfied with my performance as U.S. Attorney. He said that he was not at all dissatisfied. He said the move was solely prompted by Jay Clayton's desire to move back to New York and the administration's desire to keep him on the team."

After the meeting, Berman said, he contacted a private attorney to represent him in case he was fired. "I wanted to be ready to challenge the firing in court on the ground that I was appointed by the Court of the Southern District of New York and therefore could not be fired by the Attorney General or the president," he said.

Berman said he had spoken with Barr on the phone later that evening and asked Barr to give him until Monday, and that Barr offered him the role of SEC chairman. "I told him my position was unchanged and that I wanted to wait until Monday to have our final conversation," Berman said.

Several hours after the phone call, Barr issued a press release late Friday evening that said Berman was "stepping down."

Earlier that day, however, Berman and Barr had met privately in person at a Manhattan hotel, where Barr asked him to leave his position -- and Berman refused.

That night, following Barr's press release, Berman issued his own statement, saying Barr's announcement was the first he had heard of his purported departure. "I have not resigned, and have no intention of resigning, my position," Berman wrote.

The following afternoon, Barr said in a letter that he had asked Trump to fire Berman, and Trump had agreed to do so. Barr provided no justification for wanting Berman removed.

The bitter episode was a hurried and messy end to Berman's tenure, but his tensions with Barr stretched back nearly to the start of Barr's leadership. The two clashed over specific cases, notably the prosecution of Turkish bank Halkbank, but their relationship also suffered due to more general concerns, including Barr's attempt to micromanage certain matters.

Under Berman, the Manhattan US attorney's office had prosecuted or investigated a number of high-profile and politically sensitive matters, including the case against former Trump personal attorney Michael Cohen and an ongoing probe of Trump confidant Rudy Giuliani. In the months prior to Berman's departure, prosecutors in the office had expressed suspicions that Barr was funneling other politically sensitive cases to other federal prosecutors' offices.

Berman's successor is his former deputy, Audrey Strauss, who is now acting US attorney for the Southern District of New York -- after Barr initially had sought to install Carpenito, a prosecutor close to Barr who is the US attorney in New Jersey, to serve as Berman's acting replacement.

House Judiciary Chairman Jerry Nadler said at last month's hearing that the Berman firing was part of a pattern of misconduct involving Barr.

"If this had been an isolated incident -- if the attorney general had simply misjudged the situation and thought that Mr. Berman would go quietly -- then we might chalk up this episode to simple miscommunication and incompetence," the New York Democrat said. "But make no mistake: this was not an isolated incident."

Barr is scheduled to appear before the House Judiciary Committee on July 28 for a general oversight hearing, in what will be his first appearance before the panel since his confirmation as attorney general in February 2019.

This story has been updated with additional details.