Former Trump campaign chairman Paul Manafort spends at least 23 hours a day in solitary confinement, according to a new court filing.

Attorneys for Manafort made the claim Thursday in the District of Columbia Circuit Court of Appeals, where they are appealing a federal judge’s decision to jail their client. The 69-year-old is currently at the Northern Neck Region Jail, a roughly two hours’ drive south of Washington.

“Mr. Manafort, moreover, is now housed in solitary confinement because the facility cannot otherwise guarantee his safety. He is locked in his cell for at least 23 hours per day (excluding visits from his attorneys), at a facility approximately two hours from his legal team,” his lawyers wrote.

Manafort is facing two federal criminal trials: one set to begin July 25 in Virginia and the other set to begin September 17 in Washington, and he has pleaded not guilty in both. He faces a handful of charges including bank and tax fraud and failure to register as a foreign agent in both districts stemming from special counsel Robert Mueller’s investigation into Russian interference in the 2016 election.

Jailing Manafort has made it “effectively impossible” for him to prepare for the two trials, his lawyers argued. The decision to jail Manafort was ordered in June by U.S. District Judge Amy Berman Jackson for obstruction of justice and witness tampering, but his lawyers also said that decision went too far.

“The detention order — which has already prejudiced Mr. Manafort’s trial preparation profoundly — is fatally flawed," they wrote. "The district court did not assess the weight of the evidence against Mr. Manafort, which was weak, despite a statutory requirement to do so.”

Manafort was sent to jail despite evidence of that was “so thin as to border on non-existent,” his lawyers added.

Federal prosecutors with Mueller’s team argue that Manafort and Konstantin Kilimnik, a longtime business associate, reached out to two men who were part of Manafort’s lobbying company, Alan Friedman and Eckart Sager. Reaching out to them via phone calls, text message and encrypted apps was witness tampering, they said, and Jackson agreed on June 15 by revoking his bail and sending him behind bars.

“None of those contacts come anywhere close to an 'attempt to influence, delay, or prevent the testimony of any person,'” Manafort’s lawyers said Thursday. “The alleged communications provide the flimsiest evidence of alleged obstruction.”