Federal prosecutors on Tuesday said they did not oppose Rick Gates' request for a sentence of probation on charges brought by the special counsel's office, as they commended the former top Trump campaign adviser's "extraordinary assistance" with the investigation into Russian interference in the 2016 election.

In a court filing ahead of his sentencing next week, prosecutors said Gates deserves a "significant downward departure" from guidelines that would otherwise call for him to serve about four years, or longer, in prison.

"Under exceedingly difficult circumstances and under intense public scrutiny, Gates has worked earnestly to provide the government with everything it has asked of him and has fulfilled all obligations under his plea agreement," prosecutors said in a sentencing memo submitted Tuesday in Washington's federal trial court.

Gates, represented by Sidley Austin partner Tom Green, asked Monday for a sentence without prison time.

Prosecutors said Gates' cooperation continued in spite of the "particularly turbulent environment" that came with him being called to testify against former Trump campaign chairman Paul Manafort, his onetime business associate, along with other powerful individuals.

"Gates received pressure not to cooperate with the government, including assurances of monetary assistance," prosecutor Molly Gaston wrote in Tuesday's filing.

The government documented Gates' cooperation with the government as part of a nearly two-year saga in which he appeared as a star witness in prosecutions connected to Special Counsel Robert Mueller III's investigation. Prosecutors said they do not oppose Gates' request for a sentence of probation.

Gates, 47, agreed to cooperate with the special counsel's office last year after admitting to a raft of offenses, including financial fraud and lying to investigators.

In the ensuing months, he took the witness stand in trials linked to Mueller's probe, including the prosecution of Gates' longtime business associate, Paul Manafort, that resulted in the former Trump campaign chairman's conviction on financial fraud and other charges stemming from his past work for the Russia-aligned government of Ukraine.

Green on Monday touted Gates' cooperation with the special counsel's office Monday in a court filing that urged U.S. District Judge Amy Berman Jackson of the District of Columbia to impose a probation-only sentence.

"We believe that the parties are in agreement that Mr. Gates has fulfilled every obligation he agreed to (and then some) and that he has devoted enormous energy and commitment to this task while telling the truth and maintaining his composure," Green told the court. "His time spent with [the special counsel] and other federal and state prosecution offices totals over 500 hours. He has responded to three congressional subpoenas and has been interviewed by congressional staff."

Gates more recently took the witness stand in the trials of Greg Craig, a prominent Washington lawyer who served as President Barack Obama's first White House counsel, and Roger Stone, a longtime Trump confidant widely known as a political trickster. Craig was acquitted, a fact that prosecutors noted in Tuesday's filing.

greg Craig Former Obama White House Counsel Gregory Craig leaves federal court in Washington, D.C., on Aug. 22, 2019. Credit: Diego M. Radzinschi /ALM

"Although Craig was acquitted, Gates' testimony was corroborated and credible, and the government believes that Gates testified truthfully and completely in that case," prosecutors said in their sentencing memo. "Gates' assistance should be evaluated independent of the jury's decision—he should be given no more or less credit for his cooperation in that matter than had Craig been found guilty."

Last month, Gates took the stand in the trial of Stone, who was found guilty of tampering with a witness and lying to Congress about his efforts to learn of hacked Democratic emails during the 2016 presidential election.

Gates described during the trial how the Trump campaign viewed Stone as a conduit of sorts to WikiLeaks, the anti-secrecy group that strategically released the hacked files to benefit Trump's campaign.

In one of the trial's most revealing moments, Gates recalled overhearing a phone call between Trump and Stone in July 2016, just days after WikiLeaks released a trove of emails that were embarrassing to Hillary Clinton's campaign. Gates testified that, after hanging up, Trump said "more information" would be coming.

"He should be commended for standing up to provide information and public testimony against individuals such as Manafort, Craig, and Stone, knowing well that they enjoy support from the upper echelons of American politics and society," Gaston wrote Tuesday.

Gates is scheduled to be sentenced Dec. 17.