President Trump’s in-house lawyer representing him in Special Counsel Robert Mueller’s probe is set to leave this month -- and will be replaced by an attorney who represented former President Bill Clinton during his impeachment fight, Fox News has learned.

Cobb, who sports a trademark mustache, served as the president’s internal legal counsel and acted as a liaison between the White House and Mueller’s office. White House Counsel Don McGahn advises Trump internally on separate matters.

Cobb will now be replaced by Emmet Flood, who served as counsel for Clinton during impeachment proceedings in 1998. Flood also was the lead lawyer at the White House Counsel’s Office during former President George W. Bush’s second term. Flood is a partner at Williams & Connolly -- the law firm also represents Hillary Clinton, and did so during the FBI's investigation into her private email server.

“For several weeks Ty Cobb has been discussing his retirement and last week he let Chief of Staff Kelly know he would retire at the end of this month,” White House Press Secretary Sarah Sanders said in a statement on Wednesday, adding that "Emmet Flood will be joining the White House Staff to represent the president and the administration against the Russia witch hunt."

Sanders said Cobb has done a "terrific job."

Cobb tirelessly defended the president, repeatedly stating that the president “is not considering or discussing the firing of Special Counsel Robert Mueller.”

Cobb’s retirement comes weeks after former New York mayor Rudy Giuliani joined Jay Sekulow on the president’s legal team defending him in Mueller’s probe into Russian meddling and potential collusion with Trump campaign associates during the 2016 presidential election. Giuliani has vowed to reach a “resolution” with the special counsel.

Trump’s legal team has been in flux over the last several months, amid John Dowd’s resignation. Dowd was Trump’s lead attorney on his legal team, and voiced strong opposition to Trump doing an interview with Mueller.

On Tuesday, Fox News obtained a list of questions Mueller was slated to ask Trump, should they sit down for an interview. The questions, first obtained and reported by The New York Times, cover Trump's motivations for firing James Comey a year ago, as well as his reaction to Attorney General Jeff Sessions' recusal from the Russia investigation.

Dowd also told The Associated Press Tuesday night that Mueller raised the possibility of a subpoena during a meeting with Trump's legal team in March. According to accounts of the meeting first reported by The Washington Post and confirmed by Fox News, Dowd retorted: "This isn’t some game. You are screwing with the work of the president of the United States."

In between Cobb’s decision to retire and Dowd’s resignation, the president considered adding former U.S. attorney Jospeh diGenova to his outside legal team representing him in the Mueller probe, as well as diGenova’s wife and law partner, Victoria Toensing. Due to a conflict of interest, the duo was unable to formally advise the president in the investigation.

Fox News' Serafin Gomez contributed to this report.