Sharon Bialek arrives for a news conference where she accused Republican presidential candidate Herman Cain of sexual harassment on November 7, 2011 in New York City.
Republican presidential hopeful Herman Cain, already hit with sexual harassment allegations by three unidentified women, was accused for the first time in public by a woman who said he groped her.
Addressing a packed press conference in Manhattan, Sharon Bialek spoke in detail about how Cain put his hand up her skirt and grabbed her in a sexually suggestive way in a car after taking her out to dinner in Washington in 1997.
Bialek, standing with high-profile attorney Gloria Allred in an ornate room at New York's exclusive Friars Club, said the alleged harassment took place when she had sought Cain's assistance after losing her job in the National Restaurant Association, which he headed.
"He suddenly reached over and he put his hand on my leg under my skirt and reached for my genitals. He also grabbed my head and brought it towards his crotch," Bialek said.
"I was very, very surprised and very shocked. I said, 'What are you doing? You know I have a boyfriend. This isn't what I came here for.' Mr Cain said, 'You want a job, right?'"
The new accusation could deal a blow to Cain's surprise success in the race, where he is vying with the more establishment candidate Mitt Romney, a former Massachusetts governor, for the nomination to take on President Barack Obama.
"I want you, Mr Cain, to come clean. Admit what you did," Bialek said, reading from a lengthy statement in the glare of camera lights, while Allred stood at her side.
Cain's campaign responded almost instantaneously, saying in a statement: "All allegations of harassment against Mr Cain are completely false. Mr Cain has never harassed anyone."
"Just as the country finally begins to refocus on our crippling $15 trillion national debt and the unacceptably high unemployment rate, now activist celebrity lawyer Gloria Allred is bringing forth more false accusations against the character of Republican front-runner Herman Cain," the statement said.
Until now, the reports about skeletons in Cain's closet, which began just over a week ago, have failed to make much of an impact. Cain has reacted mostly by stonewalling media queries, sometimes angrily.
Latest polls showed him tied or just ahead of Romney, who most analysts have predicted will ultimately become the Republican candidate. One ABC News/Washington Post poll shows Cain behind by a single percentage point.
Allred, who describes herself on her website as a "fearless lawyer, feminist, activist, television and radio commentator, warrior, advocate, and winner," said Bialek was not interested in a lawsuit against Cain or other financial gain.
"She could have attempted to sell her story, but chose not to do so," Allred said. "If all of these allegations by all of the women who have been reported to have made them are true, then I, for one, am disgusted at Mr Cain's serial sexual harassment of women."
Cain, the former chief executive of Godfather's Pizza, who has never before held elected office, is vying to be the party's first African American nominee. If he succeeded, the right-wing Tea Party favorite would then set up the first all-black presidential race in US history.
Washington news website Politico broke the sexual harassment allegation story, reporting on harassment complaints from two women also dating back to the 1990s, when Cain headed the National Restaurant Association.
One accuser, who reportedly received a settlement worth $45,000, issued a statement on Friday through her lawyer saying Cain had made a "series of inappropriate behaviors and unwanted advances."
Despite being released from the confidentiality clause in her original settlement, the woman, now a government employee, said she wished to remain anonymous.
Cain belatedly conceded that he was aware that a female employee at the association had received a paid settlement.
He denied any knowledge of a second alleged case and maintains he is completely innocent. A third incident was also reported in the US media.
"She felt she needed to speak out," Allred said of Bialek in an interview with CNN.
"Our message is sexual harassment is wrong. It matters. It hurts women. And in the words of my client, it is time for Mr Cain to come clean."