The 27-year-old freelance journalist said to have had an affair with Senator John Kerry yesterday joined him in flatly denying the rumours, describing them as "completely "false."
At the same time her parents - earlier reported by The Sun newspaper in Britain to have called theDemocratic front-runner "a sleazeball" - issued a separate statement describing the allegations as a lie, and adding that they intended to vote for Mr Kerry in the forthcoming presidential campaign.
The story has electrified newsrooms around the world since it first appeared on the right-wing internet news service the Drudge Report. In the US, the allegations did not make their way beyond right-wing talk radio and the tabloid press.
Abroad, however, it gained wider coverage, not least because Drudge broke the Monica Lewinsky affair, which proved to be true, in January 1998.
But in a statement from Nairobi where she is visiting the parents of her fiance, Alexandra Polier told the Associated Press: "I have never had a relationship with Senator Kerry."
She added that, contrary to reports, "I never interned or worked for John Kerry. Whoever is spreading these rumours and allegations does not know me."
Her statement, which follows an equally categorical denial by Mr Kerry himself, does not resolve the mystery of where the story originated.
Some Democrats saw it as an early start to Republican "dirty tricks" ahead of what is likely to be a no-holds-barred general election campaign.
Asked about the report on Friday, Mr Kerry said on the campaign trail in Wisconsin ahead of today's primary: "I deny it categorically. It's untrue. And that's the last time I intend to respond to questions about it."
