Federal prosecutors have asked a judge to further postpone former Trump campaign aide Richard Gates’s sentencing, suggesting in a new filing that he may be a trial witness against former Obama White House counsel Gregory Craig and Trump ally Roger Stone Roger Jason StoneThe agony of justice Our Constitution is under attack by Attorney General William Barr Justice IG investigating Stone sentencing: report MORE.

In a joint status report with Gates’s defense attorneys on Monday, federal prosecutors in Washington, D.C., wrote that Gates "continues to cooperate with the government as required by his Plea Agreement."

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The filing also explicitly cites the upcoming trials of Craig and Stone in asking that Gates’s sentencing be delayed.

"As a result, the parties do not believe that a sentencing date should be set at this time," the filing states. "Accordingly, the parties respectfully request that they provide a joint status report no later than August 30, 2019."

Federal Judge Amy Berman Jackson approved their request on Tuesday.

Gates, 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’s ex-business partner and President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE’s deputy campaign chairman, pleaded guilty to charges of conspiracy and making false statements to federal investigators. He agreed to cooperate with 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 investigation more than a year ago.

He provided information relevant to Mueller’s now shuttered investigation into Russia's election interference and is cooperating with "several ongoing investigations," according to prior court filings.

Prosecutors have repeatedly sought to delay Gates’s sentencing, an indication they are still debriefing him for information or expect him to testify against defendants in the future. Monday’s filing is the clearest indication yet that Gates is expected to again take the witness stand. Gates already testified against Manafort in federal court in Alexandria, Va., a trial that ended last summer with a jury convicting Manafort of bank and tax fraud.

Craig was indicted in April on charges he made false statements to investigators and hid details about his work for Ukrainian officials. Gates worked with Craig in the course of his lobbying work for pro-Russian politicians in Ukraine.

Mueller reportedly handed off his case to the Southern District of New York before it was passed to federal prosecutors in D.C. Craig has pleaded not guilty, and his trial is slated to begin Aug. 12.

Separately, Stone was charged by Mueller in February with lying to Congress about his contacts regarding WikiLeaks, obstruction and witness tampering.

Stone only briefly worked on the Trump campaign in 2015 but maintained contact with campaign officials, and he is accused of lying about his contacts with senior campaign officials about WikiLeaks releases in testimony before the House Intelligence Committee, among other things. Stone has also pleaded not guilty, and his trial is scheduled for Nov. 5.

It remains unclear what other investigations Gates may be cooperating on.

Mueller’s prosecutors handed off Gates’s case to the U.S. attorney’s office in D.C. after shuttering the special counsel probe in late March. Mueller did not find evidence to charge members of Trump’s campaign with conspiring with Russia and did not reach a conclusion on whether Trump obstructed justice.

Mueller’s final report repeatedly references Gates’s testimony in laying out contacts between the Trump campaign and Russians and Kremlin-linked individuals.

Mueller referred 14 instances of potential criminal activity to law enforcement in other districts that fell outside his mandate to investigate Russia's interference. Only two of those were revealed in his redacted 448-page report, including the Craig case as well as the case involving former Trump lawyer Michael Cohen Michael Dean CohenJudge orders Eric Trump to comply with New York AG's subpoena before Election Day A huge deal for campaign disclosure: Trump's tax records for Biden's medical records Our Constitution is under attack by Attorney General William Barr MORE. Details on the 12 other matters are redacted; it is unclear whether they will ultimately yield criminal charges.

—Updated Tuesday at 10:44 a.m.