His detractors included an increasing number of fellow Virginia Democrats, including at least six members of the state’s congressional delegation and former Gov. Terry McAuliffe.

Some raised pointed questions about whether he remained fit to succeed Gov. Ralph Northam, who has been under pressure to resign over his acknowledgment that he once wore blackface.

Fairfax, who until this week was a rising star in Virginia politics and only the second black man ever elected to statewide office, denied any wrongdoing and vowed not to quit. But his political standing appeared to be in a free fall by Friday night, when the Democratic caucuses in the state House and Senate said that Fairfax needed to quit.

“Due to the serious nature of these allegations, we believe Lt. Gov. Fairfax can no longer fulfill his duties to the Commonwealth,” the caucuses said in a statement. “He needs to address this as a private citizen. The time has come for him to step down.”

Earlier in the evening, Fairfax faced cascading calls from Washington for his exit.

“Given recent developments, I believe that it is best for the Commonwealth of Virginia if Justin Fairfax dealt with these accusations as a private citizen,” Rep. A. Donald McEachin, an African-American Democrat whose district includes Richmond, the Virginia capital, wrote on Twitter. “He can no longer serve us as the lieutenant governor of Virginia.”

Minutes later, five more Democratic members of Congress from Virginia demanded that Fairfax step down, citing a series of accusatory public statements and an NBC News report that Fairfax used a harsh obscenity to describe one of the women who accused him of sexual assault.

“Lt. Governor Fairfax has also shown exceptionally poor judgment in his handling of these allegations,” the lawmakers — Don Beyer, Gerry Connolly, Elaine Luria, Abigail Spanberger and Jennifer Wexton — said in a scathing joint statement. “He repeatedly attacked his accuser, he reportedly used vile and degrading language to describe her, he mischaracterized an investigation into the encounter, and he sought to blame others for events in his own past. These actions do not meet the standard to which we hold Virginia’s highest elected officers.”

Fairfax, 39, who only last weekend seemed imminently poised to become governor, has been under siege in recent days as speculation about his personal behavior coursed through the Capitol. On Wednesday, Vanessa Tyson, a college professor from California, used a 2 1/2-page statement to detail how an episode of consensual kissing in 2004 “quickly turned into a sexual assault,” including forced oral sex.

On Friday afternoon, a lawyer for a second accuser, Meredith Watson, said that Fairfax had raped Watson when they were students at Duke University in 2000.

“Mr. Fairfax’s attack was premeditated and aggressive,” the lawyer, Nancy Erika Smith, said in a statement. Although Smith did not describe Watson’s account as exhaustively as Tyson did hers, the lawyer said that “the details of Ms. Watson’s attack are similar to those” that Tyson had put forward.

In interviews with voters around Richmond on Friday, Fairfax still had scattered support. The clientele at Genesis Barbershop downtown looked up at the TV and saw a man who, they said, had gotten his haircut there just a week earlier. The news about their customer — Fairfax — wasn’t good.

“He’s done,” muttered a 59-year-old man who gave his name only as Coach. “Two women? With all that #MeToo stuff?”

Everyone agreed that the politics had gotten much dirtier, that it was all bad for the state. But they also questioned why these allegations seemed to come out in one big wave.

“It’s all happening at the same time for a reason,” said Patrick Jones, a 51-year-old pastor whose son was getting a haircut. This was a scheme by the Republicans, he contended.

“The people putting this out there don’t care about any of this,” he said. “They only care about putting a bad name on the Democratic leadership and winning back the state.”

In a telling indication of the lieutenant governor’s mounting political vulnerability, many of the fiercest demands for Fairfax’s resignation were coming from Democrats. And even before Watson came forward Friday afternoon, few people at the Capitol were offering the lieutenant governor their full-throated support — a remarkable abandonment of a man who was preparing to run for governor in 2021.

Tyson’s account, some legislators said, had rung true.

“She’s very credible, and I’m very disturbed,” Delegate Charniele Herring, the chairwoman of the House Democratic Caucus, said of Tyson a few hours before Watson’s lawyer released her statement.

Herring, who is black, rejected concerns that Fairfax was a victim of racial stereotypes.

“What I see is a male who has been accused of sexual assault, period,” she said. “But I am a fair person, and I believe we need to hear from him. But I am very concerned.”

Herring could not be reached for comment about Watson’s claim, which was released just hours after lawmakers recessed for the weekend.

But McAuliffe on Friday called for Fairfax to quit — a public distancing that could give other Democrats political cover.

“The allegations against Justin Fairfax are serious and credible,” McAuliffe wrote on Twitter. “It is clear to me that he can no longer effectively serve the people of Virginia as Lieutenant Governor.”

The Virginia Legislative Black Caucus, a powerful bloc within the General Assembly, said Friday night that it was “best” for Fairfax to resign.

“While we believe that anyone accused of such a grievous and harmful act must receive the due process prescribed by the Constitution, we can’t see it in the best interest of the Commonwealth of Virginia for the lieutenant governor to remain in his role,” the caucus said in a statement.

By Friday evening, Patrick Hope, a Democratic legislator from Northern Virginia, threatened grave political consequences for Fairfax: articles of impeachment, which he vowed to introduce Monday if the lieutenant governor did not quit.

Among national Democrats, Sen. Cory Booker of New Jersey, who is running for president, called on Fairfax to resign Friday night, and several other 2020 candidates have called for investigations into the assault allegations.