Special Counsel Robert Mueller is continuing its Russia probe on multiple fronts, with former Trump campaign aide Rick Gates reportedly cooperating with prosecutors on "several ongoing investigations."

Mueller’s two-paragraph legal filing on Wednesday indicated that the investigation into the alleged collusion between Russia and the Trump campaign is far from over.

The filing noted that Gates, who earlier this year pled guilty to one count of conspiracy against the U.S. and one count of making false statements to FBI agents, is still working with prosecutors on multiple investigations, making his sentencing at the time not appropriate, Bloomberg reported.

Gates famously testified during the trial of former Trump campaign manager Paul Manafort, admitting both of them committed crimes. He was a key witness in ensuring Manafort would plead guilty to charges and agree to cooperate with the Mueller probe.

The revelation of such filing came as the top members of the U.S. Senate torpedoed a legislation aimed at protecting Mueller’s investigation from any meddling by President Trump.

FLAKE VOWS TO BOYCOTT GOP JUDICIAL NOMINEES AFTER MCCONNELL TORPEDOES MUELLER PROTECTION LEGISLATION

Senate Majority Leader Mitch McConnell blocked a bill by outgoing Arizona Republican Sen. Jeff Flake and Delaware Democratic Sen. Chris Coon.

In a statement, Flake dismissed suggestions that his bill is not necessary, saying the resignation of Attorney General Jeff Sessions and the appointment of Matthew Whitaker as the acting Attorney General indicates the Mueller investigation could be “jeopardy.”

“With the firing of the attorney general ... the president now has this investigation in his sights and we all know it,” Flake said. “How such an investigation can be the cause of controversy is beyond me. ... Presidents do not get to determine what gets investigated and what and who does not.”

"With the firing of the attorney general ... the president now has this investigation in his sights and we all know it,” Flake said. “How such an investigation can be the cause of controversy is beyond me. ... Presidents do not get to determine what gets investigated and what and who does not." — Arizona Republican Sen. Jeff Flake

Whitaker has been facing calls to recuse himself from the Russia probe due to his criticism of the investigation.

DOJ SAYS MATTHEW WHITAKER CAN SERVE AS ACTING ATTORNEY GENERAL

Others, like the State of Maryland, filed a legal motion on Tuesday for an injunction declaring Whitaker’s appointment illegal, arguing that deputy attorney general Rod Rosenstein is the rightful acting attorney general and “must be named” as such.

But the Justice Department Office of Legal Counsel issued an opinion on Wednesday, saying Trump’s appointment of Whitaker was consistent with the Federal Vacancies Reform Act (VRA) of 1998 that allows the president to temporarily fill a position that requires Senate confirmation with any official who’s been in the department for over 90 days.

Fox News’ Brooke Singman contributed to this report.