Washington(CNN) Special counsel Robert Mueller is aware of an unsuccessful attempt by President Donald Trump to lobby Attorney General Jeff Sessions not to recuse himself from the Justice Department's Russia probe, The New York Times reported Thursday.

The Times, citing two people with knowledge of the episode, said Trump had ordered White House counsel Don McGahn last March to stop Sessions from recusing himself from oversight of the investigation into Russian interference in the 2016 election. A source close to Sessions confirmed to CNN Friday that McGahn reached out to the attorney general in an attempt to dissuade him.

Trump's reported attempt to have a political ally maintain control of an investigation into his associates would add to a list of possible examples of Trump seeking to influence the Justice Department -- and opening himself up to potential obstruction of justice claims.

Ty Cobb, a lawyer for the President, told CNN tonight he "respectfully declines to respond."

At the time, Sessions faced mounting calls for recusal given his support for the Trump campaign and the revelation of an omission during his confirmation hearing about contacts with Sergey Kislyak, who was the Russian ambassador to the US at the time.

While widely reported on, the government did not confirm the existence of the investigation until then-FBI Director James Comey told the House Intelligence Committee later in March 2017 that there was an ongoing investigation into potential coordination between Trump's associates and Russia to influence the 2016 election.

The Times also reported that, "Two days after Mr. Comey's testimony, an aide to Mr. Sessions approached a Capitol Hill staff member asking whether the staffer had any derogatory information about the FBI director," a claim that the Justice Department denied. "The attorney general wanted one negative article a day in the news media about Mr. Comey, according to a person with knowledge of the meeting," the Times reported.

But Justice Department spokeswoman Sarah Isgur Flores told CNN: "This did not happen and would not happen. Plain and simple."

New York Rep. Jerry Nadler, the top Democrat on the House Judiciary Committee, released a statement in the wake of the report, calling McGahn's reported conduct "completely unacceptable" and saying McGahn should make himself available to the committee.

"Congress needs to know exactly what efforts Mr. McGahn took to 'lobby' the Attorney General in this case, and what President Trump's role was in those efforts," Nadler said.

Sessions announced he would recuse himself from all matters relating to the investigation in early March. Politicians, including Republicans, praised the decision at the time, but Trump has publicly rebuked his attorney general and said he wished Sessions had not recused.

The Times reported Thursday that after McGahn was unsuccessful at getting Sessions not to recuse, Trump became angry and said he needed an attorney general to protect him.

Sessions' recusal left Justice Department oversight of the probe to Deputy Attorney General Rod Rosenstein, who appointed former FBI director Mueller to be special counsel after Trump fired Comey in May 2017.

Sessions said in summer 2017 he was "confident" he had made the right decision about recusal -- and as some Republicans called Thursday for his ouster, some top Democrats, in a major shift, have suggested Sessions should stay to avoid interference with the special counsel probe.