Former Trump campaign chairman Paul Manafort Paul John ManafortOur Constitution is under attack by Attorney General William Barr Bannon trial date set in alleged border wall scam Conspicuous by their absence from the Republican Convention MORE is being kept in solitary confinement for 23 hours a day to "guarantee his safety," according to documents his attorney filed in court this week.

“He is locked in his cell for at least 23 hours per day (excluding visits from his attorneys),” defense attorney Kevin Downing wrote in an appeal for Manafort's release.

ADVERTISEMENT

In addition, Downing claimed in a brief filed on Thursday that Manafort is unable to prepare for his upcoming trials while jailed. One of those trials begins later this month.

New York magazine also reported that Manafort's lawyers are also arguing for him to be released on the grounds that the witness-tampering charges he faces do not include alleged physical threats of violence.

Special counsel Robert Mueller Robert (Bob) MuellerCNN's Toobin warns McCabe is in 'perilous condition' with emboldened Trump CNN anchor rips Trump over Stone while evoking Clinton-Lynch tarmac meeting The Hill's 12:30 Report: New Hampshire fallout MORE's investigative team, opposing the request for Manafort's release, said in a separate filing that Manafort's attempt to convince two potential witnesses to lie to investigators was “no less damaging to the justice system when committed through covert corrupt persuasion than through overt violence."

Manafort was sent to Northern Neck Regional Jail in Warsaw, Va., on June 15 after Mueller asked a court to revoke Manafort's pretrial release conditions due to his alleged attempted witness tampering.

Mueller also filed a superseding indictment against Manafort. Manafort is facing charges related to financial crimes, including obstruction of justice and conspiracy to obstruct justice.

Manafort faced arraignment on the two obstruction of justice charges in June. He entered not guilty pleas for both.

Some observers have speculated that the decision to jail Manafort ahead of his trials could pressure him to cooperate with Mueller's investigation in Russian meddling and possible collusion between the Trump campaign and Russia during the 2016 election campaign.

Trump insisted last month that Manafort only worked “for a very short period of time" on his campaign.