"Come clean," Sharon Bialek challenged Cain at a news conference in New York at which she described herself as "a face and a voice" to support other accusers who have so far remained anonymous.
Cain's campaign swiftly denied Bialek's account. "All allegations of harassment against Mr. Cain are completely false," it said in a written statement.
Even so, Bialek's nationally broadcast appearance on cable television cheap jerseys marked a new and — for Cain — dangerous turn in a controversy that he has struggled for more than a week to shed. An upstart in the presidential race, Cain shot to the top of public opinion polls in recent weeks and emerged, however temporarily, as the main conservative challenger to Mitt Romney.
Accompanied by her prominent lawyer, Gloria Allred, Bialek accused Cain of making a sexual advance one night in mid-July 1997, when she had travelled to Washington to have dinner with him in hopes he could help her find work.
She said the two had finished dinner cheap soccer jerseys and were in a car for what she thought was a ride to an office building.
"Instead of going into the offices he suddenly reached over and he put his hand on my leg, under my skirt toward my genitals," she said.
"He also pushed my head toward his crotch," she added.
Bialek said she told her boyfriend, an unidentified pediatrician, custom made jerseys as well as a longtime male friend about the episode.
None of Cain's other accusers has provided details as graphic as Bialek's account. But Joel Bennett, an attorney who represents one of them, said her details were "similar in nature" to what his client encountered.
Allred, a prominent sex discrimination attorney with Democratic ties, moved preemptively to blunt any attacks on Bialek's motives. She described her client as a registered Republican, a single mother and a woman with a long and successful work history.
She also said Bialek "could have attempted to sell her story but chose not to do so," and knew that by stepping forward, she would receive scrutiny.
Court records indicate Bialek had financial difficulties a decade mlb jerseys cheap ago when she filed for bankruptcy protection and reported $4,500 in unpaid rent and $13,000 in outstanding credit card bills.
Current property records show she owns a house on an acre of land in a Chicago suburb.
Some of Cain's allies immediately made a target of Allred, a Democratic campaign donor, rather than focusing any anger on Cain's accuser.
Georgia state Sen. Joshua McKoon, who has endorsed Cain, accused Allred of "carnival theatrics" fueled by a partisan agenda.
"Her involvement makes it clear that it's a political smear job orchestrated by those on the left because there is nothing more terrifying than Herman Cain as the Republican nominee," the Republican lawmaker said.
But Doug Heye, a political consultant who is unaligned in the GOP race, Rolato said Bialek's allegations "are different because they involve a name and specific details."
He said Allred's involvement "is going to make some people disbelieve the charges out of hand because of the side show she creates. But Herman Cain has to be clear and convincing in his response."
Some Republicans, including presidential rival Jon Huntsman and Mississippi Gov. Haley Barbour, have urged Cain to respond more fully to the charges, and Bialek's appearance in New York was likely to add to the clamor.
Cain had an appearance scheduled for later in the day on the Jimmy Kimmel show, his only public event of the day.
Before Bialek stepped to the microphone, the allegations involved two women who had worked at the National Restaurant Association, both of whom filed sexual harassment complaints.
A third woman told The Associated Press last week that she considered filing a workplace complaint against Cain over what she deemed sexually suggestive remarks and gestures that included a private invitation to his corporate apartment.
A former pollster for the restaurant association has said he witnessed yet cheap jerseys another episode involving a fourth woman. It was unclear whether that woman is Allred's client.
Allred has represented several high-profile clients, including Amber Frey, a witness against convicted California killer Scott Peterson. Allred also represented a woman whom news reports accused of having an affair with golfer Tiger Woods.
"I consider sexual harassment the No. 1 problem in the workplace," she told the AP in an interview last week. "It denies equal opportunity in the workforce. If (women) don't protest it, they'll have to continue to suffer."