A judge on Thursday rejected a motion from former Trump campaign chairman Paul Manafort to modify the terms of his bail agreement.

U.S. District Court Judge Amy Berman Jackson wrote in court documents that Manafort's proposal to pledge his property in Alexandria, Va., as part of his $10 million bond was "unsatisfactory," as the property is already pledged as collateral for a loan on one of Manafort's other properties.

Herman Jackson also ruled that Manafort must prove he is current with his mortgage payments on another property located on New York's Fifth Avenue in order for it to be pledged as part of his bond.

The news follows reports that Manafort's former business associate Richard Gates has agreed to cooperate with special counsel Robert Mueller's team of prosecutors in their case against the former Trump aide, who was charged along with Gates last year with money laundering and tax fraud.

Gates and Manafort have both plead not guilty. Gates, however, could change his plea "within the next few days," according to a source close to the talks between Mueller's team and Gates's lawyers.

Gates hired a top white-collar Washington defense attorney last month, who has been seen meeting with Mueller's team multiple times while the businessman's other lawyers have filed to vacate the case, arguing they can no longer represent him.

On Wednesday, Mueller made a new filing under seal in Manafort's case just days after telling the judge that his team had discovered evidence of "additional criminal conduct" from the former Trump campaign chief after the court made its initial bail determination.

"That criminal conduct includes a series of bank frauds and bank fraud conspiracies," prosecutors wrote in a court filing last week.

"At the next bail hearing, we can proffer to the Court additional evidence related to this and the other bank frauds and conspiracies, which the Court may find relevant to the bail risk posed by Manafort," they continued.