Lt. Gov. Justin Fairfax (D-VA) was placed on leave from his law firm Friday after retaining outside counsel to investigate sexual assault allegations leveled against him.

“We take the allegations against Justin very seriously,” Morrison & Foerster chairman Larren Nashelsky said in a statement to the The National Law Journal. “As a firm, we believe that it is important to seriously listen to any allegation of sexual assault or harassment, and to treat all persons making such allegations with respect and sensitivity.”

Morrison & Foerster will not say who the outside counsel conducting the probe is.

Fairfax faces calls to resign from his post after two women issued statements last week detailing their allegations of sexual assault. On Wednesday, California professor Dr. Vanessa Tyson went public with her allegation against Fairfax, claiming he forced her to perform oral sex on him during the 2004 Democrat National Convention in Boston. Fairfax’s second accuser, Meredith Watson, alleged Friday that the embattled Virginia Democrat raped her at Duke University in 2000.

Several high-profile Democrats, including presidential contenders Sens. Cory Booker (D-NJ) and Elizabeth Warren (D-MA), have called on Fairfax to step aside. “The multiple detailed allegations against the Lt. Gov. of Virginia are deeply troubling,” Booker wrote on Twitter Friday evening. “They are serious, credible, and corroborated by others. It is no longer appropriate for him to serve. He should resign.”

On Saturday, Virginia’s embattled lieutenant governor called for an FBI investigation into the sexual assault allegations and pushed back against calls for him to resign, asking his detractors for “space in this moment for due process.”

“This has been a devastating week for my family. It has been an especially devastating time for the great Commonwealth of Virginia,” he said. “I say again without reservation: I did not sexually assault or rape Meredith Watson, Vanessa Tyson or anyone else. Our American values don’t just work when it’s convenient — they must be applied at the most difficult of times.”

The allegations against Fairfax have thrown Virginia politics into chaos. The lieutenant governor was tipped to replace Gov. Ralph Northam (D-VA), who faces calls to resign after a racist photo in his 1984 medical yearbook surfaced. Northam refuses to step aside, telling CBS’s Gayle King over the weekend that Virginia needs a leader with a “moral compass.” Virginia Attorney General Mark Herring is also under fire for admitting to wearing blackface while an undergraduate student at the University of Virginia.