The political crisis in the US state of Virginia has spun out of control with the state’s attorney general confessing to a blackface incident in the 1980s and a woman going public with detailed allegations of sexual assault against the lieutenant governor.

With Governor Ralph Northam’s career already hanging by a thread over a racist photo in his 1984 medical school yearbook, the day’s developments threatened the careers of all three of Virginia’s top elected officials, all of them Democrats.

The twin blows began with state attorney general Mark Herring issuing a statement admitting he wore brown make-up and a wig in 1980 to look like a rapper during a party when he was a 19-year-old student at the University of Virginia.

Governor Klan Blackface
A protest in Richmond calling for Governor Ralph Northam to resign (Shelby Lum/AP)

Mr Herring, who has been among those calling on Mr Northam to resign, said that he was “deeply, deeply sorry” about the costume and that the days ahead “will make it clear whether I can or should continue to serve”.

Then, within hours, Vanessa Tyson, the California woman whose sexual assault allegations against Lieutenant Governor Justin Fairfax surfaced earlier this week, put out a detailed statement saying Mr Fairfax forced her to perform a sex act on him in a hotel room in 2004 during the Democratic National Convention in Boston.

Ms Tyson disclosed her name in the statement.

Ms Tyson, a 42-year-old political scientist who is on a fellowship at Stanford University and specialises in the political discourse of sexual assault, said, “I have no political motive.

“I am a proud Democrat.”

Governor Klan Blackface
Virginia Lieutenant Governor Justin Fairfax (Steve Helber/AP)

“Mr Fairfax has tried to brand me as a liar to a national audience, in service to his political ambitions, and has threatened litigation,” she said.

“Given his false assertions, I’m compelled to make clear what happened.”

Mr Fairfax, who is in line to become governor if Mr Northam resigns, has repeatedly denied her allegations, saying that the encounter was consensual and that he is the victim of a strategically timed political smear.

“At no time did she express to me any discomfort or concern about our interactions, neither during that encounter, nor during the months following it, when she stayed in touch with me, nor the past 15 years,” he said in a statement.

Ms Tyson said she suffered “deep humiliation and shame” and stayed quiet about the allegations as she pursued her career, but by late 2017, as the #MeToo movement took shape and after she saw a news article about Mr Fairfax’s campaign, she took her story to The Washington Post, which decided months later not to publish a story.

The string of scandals that began when the yearbook picture came to light last Friday could have a domino effect on Virginia state government.

If Mr Northam and Mr Fairfax fall, Mr Herring would be next in line to become governor.

After Mr Herring comes House Speaker Kirk Cox, a conservative Republican.

Democrats have expressed fear that the uproar over the governor could jeopardise their chances of taking control of the Republican-dominated Virginia legislature this year.

Governor Klan Blackface
Virginia governor Ralph Northam (Steve Helber/AP)

The party made big gains in 2017, in part because of a backlash against President Donald Trump, and has moved to within striking distance of a majority in both houses.

Mr Herring, 57, went public after rumours of a blackface photo of him began circulating at the Capitol.

But in his statement, he said nothing about the existence of a photo.

The attorney general made a name for himself nationally by playing a central role in bringing gay marriage to Virginia, and he had been planning to run for governor in 2021.

If he resigns, the legislature gets to pick his replacement.

In his statement, Mr Herring said he and two friends dressed up to look like rappers they listened to, including Kurtis Blow, admitting: “It sounds ridiculous even now writing it.”

“That conduct clearly shows that, as a young man, I had a callous and inexcusable lack of awareness and insensitivity to the pain my behaviour could inflict on others,” he said.

But he also said: “This conduct is in no way reflective of the man I have become in the nearly 40 years since.”

Mr Northam has come under pressure from nearly the entire state and national Democratic establishment to resign after the discovery of a photo on his profile page in the Eastern Virginia Medical School yearbook of someone in blackface standing next to a person in a Ku Klux Klan hood and robe.

He admitted at first that he was in the photo without saying which costume he was wearing, then denied it a day later.

Governor Klan Blackface
Virginia Speaker of the House Kirk Cox, a conservative Republican, could benefit from the crisis (Steve Earley/AP)

But he acknowledged he once used shoe polish to blacken his face and look like Michael Jackson at a dance contest in Texas in 1984, when he was in the US Army.

Mr Herring came down hard on Mr Northam when the yearbook photo surfaced, condemning it as “indefensible”, “profoundly offensive” and “shocking and deeply disappointing”.

He said that it was no longer possible for Mr Northam to lead the state.

Mr Herring, who was elected to his second four-year term in 2017, announced when he first took office that he would no longer defend the state’s ban on gay marriage, saying it was time for Virginia “to be on the right side of history”.

A US federal judge overturned the ban, citing Mr Herring’s opposition, and Virginia began issuing marriage licenses to same-sex couples in 2014, nearly a full year before the US Supreme Court legalised gay marriage nationwide.