Rick Gates, center, arrives at the Prettyman Federal Courthouse on Jan. 16. (Chip Somodevilla/Getty Images)

Lawyers for Rick Gates, the co-defendant of former Trump campaign manager Paul Manafort, cited unspecified “irreconcilable differences” with their client in asking to leave the case, but a federal judge did not immediately rule on their request after a sealed hearing Wednesday.

U.S. District Judge Amy Berman Jackson of Washington took the matter under advisement after a nearly 90-minute hearing, held behind closed doors to preserve the secrecy of attorney-client communications.

Gates’s attorneys Shanlon Wu of Washington and Walter Mack and Annemarie McAvoy of New York moved Feb. 1 to withdraw as counsel in a shake-up in the pending prosecution by special counsel Robert S. Mueller III.

In filings unsealed Wednesday, the lawyers said they wanted to discuss the reason for their request in secret because it involves private, “highly sensitive matters” concerning Gates that “would potentially be prejudicial to the Defendant as well as embarrassing.”

In a separate document, they added that “irreconcilable differences have developed with the client which make our effective representation of the client impossible” but invoked the protections given to lawyers’ discussions with their clients in asking to disclose the matter in closed court.

Gates and his attorneys have not shown public signs of discord, despite drawn-out bail talks and the appearance that he has fewer financial assets than initially asserted by prosecutors.

A shift could leave Gates, 45, with his third set of attorneys since he and his former employer, Manafort, 68, were indicted Oct. 30 on fraud, conspiracy and money-laundering counts in the first disclosed charges of Mueller’s probe of Russian interference in U.S. political affairs.

The timing of the change in lawyers comes as the prosecution enters a new phase preparing for trial.

Both men have pleaded not guilty to the charges, which arose out of Manafort’s alleged secret lobbying for a Russia-friendly political party in Ukraine.

After the indictment, Gates replaced his initial attorney, Michael Dry, with Mack, of Doar Rieck Kaley & Mack in New York; Wu, of Wu, Grohovsky & Whipple in Washington; and McAvoy, a former federal prosecutor and consultant specializing in financial crime investigations.

CNN reported Jan. 23 that Gates had added prominent white-collar lawyer Thomas C. Green of Sidley Austin in Washington to his defense team after Green was spotted at Mueller’s office, fueling speculation about ongoing negotiations with prosecutors.

Wu declined to comment after the hearing, citing a court gag order in place in the case. Green did not respond to requests for comment and was not in the courtroom Wednesday.

Gates, after more than two months under house arrest, reached bail terms in January on a nearly $5 million secured bond to gain conditional release. His attorneys also are sorting through more than 640,000 pieces of evidence turned over by prosecutors.

The judge has set deadlines starting April 6 for motions challenging the indictment before scheduling a possible fall trial date.

Manafort has yet to reach a bond deal and has filed a lawsuit challenging his indictment and Mueller’s appointment as special counsel.

A cloud over trial scheduling emerged during a Jan. 16 hearing, which included a lengthy discussion at the bench by prosecutors and attorneys out of earshot of those in the courtroom seats.

“We are the least prepared of anyone here, and we want to do a good job, and we need that time to be able to do it,” Mack said in open court at one point.

Court dockets show that Mack also faces a trial date set for April 9 in Manhattan federal court in which he is defending a former Gates business associate, Steven Brown, in a fraud prosecution by the U.S. attorney’s office there. Brown’s judge set the trial date Jan. 11, shortly before Gates’s last hearing.