Lawyers for Paula Jones, 27, say they will file the charge today, just meeting a three-year deadline for such civil suits. The alleged encounter took place in a room at the Excelsior Hotel in Little Rock on 8 May 1991 during a business conference organised by Mr Clinton, who was already widely expected to run for the Democratic presidential nomination.
Ms Jones, who was a clerk at the conference, says she was asked by an Arkansas state trooper to accompany him to the room. There, she says, Mr Clinton tried to kiss her, exposed himself and asked her to perform oral sex on him.
'I will never forget the look on his face,' she was quoted as saying by the Washington Post yesterday. 'It was just red, beet red.' She says she rebuffed the advances and left the room upset and humiliated.
Eclipsed by the Gennifer Flowers saga, the allegation surfaced briefly during the 1992 campaign. It cropped up again at Christmas when former troopers went public with tales of arranging secret assignations for the governor, and then in February when Ms Jones held a press conference. Until now only conservative anti-Clinton media have touched the story.
At the White House, the charges have been categorically denied. Robert Bennett, the high-profile Washington defence lawyer hired on Tuesday by the President, insists the accusations are politically motivated lies: 'This event, plain and simple, didn't happen,' he said. Ms Jones insists it did, and two girlfriends have signed affidavits that she told them about it on the day.
If Ms Jones goes ahead, Mr Clinton must file a response in 20 days. The case could end in court if it is not thrown out and if no deal is struck. 'Basically it's a matter of credibility, his word against hers,' says a Washington attorney. 'But it's usually very hard to knock out this kind of case early on.'
Ms Jones's lawyers say the suit will allege affliction of emotional distress, violation of her civil rights, and that Governor Clinton regularly used state troopers to help him to find women for sex. According to one report, she may seek up to dollars 3m ( pounds 2m) damages.
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