Roger Stone, an informal adviser to Donald Trump before he won the White House, said Friday the president should fire special counsel Robert Mueller and Deputy Attorney General Rod Rosenstein.

"I'd fire Mueller and Rosenstein for wasting the taxpayers' money. This is a witch hunt," Stone said, parroting a line from Trump.

Stone suggested Trump take such action during an interview with CNNMoney at the Cannabis World Congress and Business Exposition in New York.

Mueller, a former FBI director, is currently overseeing the probe into Russian meddling in the 2016 election.

Though Mueller is leading the investigation, Rosenstein still addresses matters related to the probe, since Attorney General Jeff Sessions recused himself from the investigation. Rosenstein appointed the special counsel, whose budget comes from the Justice Department.

Stone has been named as part of the investigations into Russian meddling in the 2016 elections, and he sent documents to the Senate Select Committee on Intelligence last month. The panel asked Stone, former Trump campaign manager Paul Manafort, campaign foreign policy adviser Carter Page and former national security adviser Michael Flynn for information about their Russian contacts and business dealings.

Like Trump, Stone also told CNNMoney there was no evidence that the Trump campaign colluded with Russia, and said he would testify in an open session "if they would let me testify in public."

Stone's advice came days after Chris Ruddy, a close friend of Trump's, said the president was considering firing Mueller.

Rep. Adam Schiff, D-Calif., the top Democrat on the House Intelligence Committee, urged Congress to intervene if Trump did take such action.

"It has become clear that President Trump believes that he has the power to fire anyone in government he chooses and for any reason, including Special Counsel Robert Mueller," he said in a statement. "That is not how the rule of law works, and Congress will not allow the President to so egregiously overstep his authority."

"If President Trump were to try to replicate Nixon's Saturday Night Massacre by firing Deputy Attorney General Rod Rosenstein in addition to Mueller, Congress must unite to stop him – without respect to party, and for the sake of the nation."

The president took to his Twitter account Friday morning to criticize the Russia investigation and appeared to attack Rosenstein.

"I am being investigated for firing the FBI Director by the man who told me to fire the FBI Director! Witch Hunt," Trump said.

Rosenstein issued a memo to the president detailing a rationale for former FBI Director James Comey's firing.

Trump seemed to be confirming a Washington Post report from Wednesday stating Mueller was investigating the president for obstruction of justice. But the White House said Trump was referring to the Washington Post's article, and not confirming he was under investigation for his decision to fire Comey.