As Virginia Governor Ralph Northam faces calls to resign over a racist photo, a woman has claimed his possible replacement sexually assaulted her.
Lt Governor Justin Fairfax, 39, has denied the assault, allegedly in 2004 at a Democratic political convention.
Mr Fairfax said the "uncorroborated smear" was meant to derail his career.
Mr Northam, meanwhile, still denies he is either of two people - one in blackface, the other in Ku Klux Klan robes - pictured on his yearbook page.
The governor and lieutenant governor are both Democrats.
A statement from Mr Fairfax's office said on Monday: "Only now, at a time of intense media attention surrounding Virginia politics, has this false claim been raised again.
"He has never assaulted anyone - ever - in any way, shape or form."
The statement added that Mr Fairfax will "take appropriate legal action" regarding "this defamatory and false allegation".
The lieutenant governor told reporters it was a "totally fabricated story, out of the blue, that's meant to attack me because of where I am in politics".
Mr Fairfax would make history as one of the few African Americans ever to become a US governor if Mr Northam were to resign over his racist photo controversy.
Big League Politics, the conservative outlet which published the claims against Mr Northam and Mr Fairfax, noted it had not spoken to the woman accusing Mr Fairfax.
The website shared what it said was a screenshot of the woman's private Facebook post about the alleged assault.
Mr Fairfax is not named in the post, which refers to a Democratic holder of statewide office who is in line for a "very big promotion".
The BBC is not identifying the woman, but has contacted her and is awaiting a response.
What is Lt Gov Fairfax accused of?
In the rotunda of the state capitol in Richmond on Monday, Mr Fairfax described the encounter as "100% consensual".
He said the woman had been "very interested" in him and "was very much into the consensual encounter".
He told reporters the woman maintained contact with him in the months that followed their interaction.
The BBC contacted Mr Fairfax for comment, but did not receive an immediate reply.
VA Lt. Gov. Justin Fairfax denies sexual assault claim, telling reporters in Richmond that he had "consensual encounter" with woman in hotel room in 2004 https://t.co/pvo4q30cCe pic.twitter.com/uhVO1VkUpr— CBS Evening News (@CBSEveningNews) February 4, 2019
The Washington Post said it had investigated the woman's claims in 2017, but did not publish a story because statements by the woman and Mr Fairfax could not be corroborated.
On Monday, the Post detailed the allegations and also noted that there had been no red flags or inconsistencies in the story, as Mr Fairfax's statement asserted.
The woman reportedly told the Post she had met Mr Fairfax in 2004 at the Democratic national convention.
After they realised they had a mutual friend, they began talking and Mr Fairfax asked her to walk back to his hotel room to retrieve some papers, according to the Post.
The woman reportedly told the paper that their encounter in the hotel room began consensually, but claimed that Mr Fairfax then held her down and assaulted her.
What's the latest with Ralph Northam?
Virginia's governor is fighting for his political life in a racism row.
Mr Northam denies he was in a photo of a man in blackface and another in Ku Klux Klan robes that appeared in his 1984 medical school yearbook page.
He first apologised on Friday and said he was one of the two people, before changing his story a day later.
He has admitted separately blackening his face to impersonate singer Michael Jackson at an event the same year, while he was at Eastern Virginia Medical School.
On Monday, the beleaguered governor met his cabinet members and reportedly implored them to give him a chance to prove he was not the person in the photo.
According to CNN, Mr Northam told the meeting he is afraid of being labelled "racist for life".
Meanwhile, a few dozen protesters gathered at the state capitol to demand the governor step down.
Former Vice-President Joe Biden has led Democratic calls for Mr Northam to resign, saying he has lost all moral authority.
African-American politicians in Virginia called the photo "disgusting", and Republicans have also urged him to resign.
Mr Fairfax has not explicitly echoed those calls, instead saying the governor should make a decision that is in Virginia's best interests.