The woman said he made sexually suggestive remarks or gestures about the same time that two co-workers had settled separate harassment complaints against Cain, who was then the head of the National Restaurant Association.
The woman was located and approached by the AP as part of its investigation into harassment complaints against Cain that were disclosed in recent days and have thrown his presidential campaign into turmoil. She spoke only on condition of anonymity, saying she feared losing her current job and the possibility of damage to her reputation.
Cain's campaign denied anew that he'd done anything wrong, decried a "smear campaign" as he is riding high in opinion polls and accused rival Rick Perry's operation of being behind the original stories.
Perry's campaign denied any involvement - and suggested the campaign of yet another candidate, Mitt Romney, might be a source. Romney's campaign said that wasn't true.
Later, Perry spokesman Ray Sullivan called the Cain campaign's assertions against Perry "both reckless and false."
"For a candidate and campaign that claim to be the victims of unfounded and unproven accusations, they are awfully quick to hurl unfounded accusations themselves. Contrary to the Cain campaign's false accusations, there is not one shred of evidence that any member of the Perry team had anything to do with the recent stories regarding Herman Cain -- because it isn't true," Sullivan said.
The woman said she did not file a formal complaint against Cain because she began having fewer interactions with him. Later, she learned that a co-worker - one of the two women whose accusations have rocked Cain's campaign this week - had already done so. She said she would have felt she had to file otherwise.
She said Cain told her that he had confided to colleagues how attractive she was and invited her to his corporate apartment outside work.
His actions "were inappropriate, and it made me feel uncomfortable," she said.
Earlier this week, amid the allegations but not addressing them specifically, Cain said he had "a sense of humor, and some people have a problem with that."
But the former employee told the AP: "People have said he's a jovial guy. But I never knew him to make jokes like that."
The AP confirmed that the employee worked at the restaurant association with Cain during the period in question, that she has no party affiliation in her voter registration in the past decade and is not identified as a donor in federal campaigns or local political campaigns. Records show she was registered as a Democrat at one point previously.
Asked for comment about the accusations, including the most recent, Cain spokesman J.D. Gordon said, "Mr. Cain has said over the past two days at public events that we could see other baseless allegations made against him as this appalling smear campaign continues." Gordon added, "He has never acted in the way alleged by inside-the-Beltway media, and his distinguished record over 40 years spent climbing the corporate ladder speaks for itself."
Later campaign manager Mark Block alleged that Texas Gov. Perry's campaign was behind the original stories on the two women and demanded an apology.
Denying any involvement, Perry spokesman Ray Sullivan says the Texan's campaign learned of the allegations when Politico first published a story late Sunday evening.
Cain himself, in an interview with Forbes, said he believed a Perry consultant gave information about the allegations to Politico. After denying earlier this week that he knew about any settlements, Cain said Wednesday that he outlined the allegations of a woman to the consultant, Curt Anderson, when Anderson was helping him on an earlier campaign.
Anderson said in a statement to AP: "I was one of several consultants on his Senate race in 2004 and was proud to help him. I never heard any of these allegations until I read about them in Politico, nor does anything I read in the press change my opinion that Herman is an upstanding man and a gentleman."
Perry's campaign pointed to former Massachusetts Gov. Romney's operation as a possible source of the Politico story. "There are real ties between Romney campaign backers and Mr. Cain and the National Restaurant Association," Sullivan said.
Romney spokeswoman Andrea Saul denied that the campaign was involved in the disclosure of the sexual harassment allegations. And Romney, himself, took a pass when asked to comment on Cain in a television interview.
Meanwhile, another woman who worked with Cain at the restaurant association, said, "I found him to be a good boss." Christina Howard, a former lobbyist for the association, said, "I felt no problem going into his office and asking for his advice."
She said she didn't recall allegations about Cain during his tenure and added, "I'd roll my eyes at anyone who would make that allegation."
But Chris Wilson, a pollster who did work for the restaurant association during Cain's tenure, said in an interview that he witnessed the businessman making inappropriate comments and gestures toward a young woman who worked for the group during a dinner at a hotel in Arlington, Va., across the Potomac River from Washington in the late 1990s. Wilson declined to discuss more specifics without the woman's permission.
Cain's behavior with women was well known, Wilson said.
"People knew about it. I'm surprised that it hasn't come up before," said Wilson, whose firm, Wilson Perkins Allen Opinion Research, does polling for a political action committee backing Perry. Wilson said he has not been the source of information on the accusations against Cain.
Throughout the day Wednesday, Cain tried to project an image of campaign business as usual, but he appeared frazzled at times and couldn't escape the questions that have dogged him since the report Sunday night that at least two women had complained about his behavior while at the restaurant association and had been given financial settlements. The controversy has arisen two months before the leadoff Iowa caucuses and as polls show Cain at the head of the GOP field alongside Romney.
"There are factions that are trying to destroy me personally, as well as this campaign," Cain said as the day began, though he didn't say to whom he was referring.
At his next appearance in suburban Virginia, he was supposed to take questions after a speech to health care professionals, but he ultimately refused.
"Don't even bother asking me all of these other questions that you all are curious about, OK? Don't even bother," a testy Cain told a throng of reporters.
When pressed, Cain raised his voice and said "What did I say? Excuse me. Excuse me!" as hotel security led him through a hallway jammed with journalists. "What part of `no' don't people understand?"
Another of Cain's accusers was increasingly reluctant speak publicly, a person close to the situation said Wednesday. The person, speaking on the condition of anonymity because of the sensitivity of the accusations, said the fact that the incident has become public was very unsettling to the woman.
By late Wednesday, it appeared that the accuser's lawyer, Joel P. Bennett, was not going to press the National Restaurant Association to waive the confidentiality agreement the accuser had agreed to as a part of her settlement so she could talk freely, as the lawyer initially had suggested he would.
Rather, Bennett told the AP in a brief email that he would seek approval Thursday from the trade group for his client to issue a statement about her position notwithstanding the confidentiality agreement.
Confidentiality agreements that commit both sides to silence are common in financial settlements of an employee's sexual harassment claims, lawyers for management and employees said. Violating such an agreement can lead to a complaint in court and an order to pay damages, or at least the other side's attorney's fees, said Sarah Pierce Wimberly, a partner in the Atlanta office of the Ford and Harrison law firm.
But when the silence is broken, it's often hard to find the source of the leak, said Robert Kelner, a partner in the Covington and Burling firm's Washington office. He said, "The truth is, when parties enter into these confidentiality agreements around a settlement, they usually understand that there is less than 100 percent certainty that the information is truly going to remain confidential."
It's not clear if Cain himself was part of the settlement or whether it just involved the association and the woman. But he almost certainly would be bound by it, as the association's former president.
Over the past two days, Cain has acknowledged he knew of one agreement between the restaurant association and a woman who accused him of sexual harassment. He has said the woman initially asked for a large financial settlement but ultimately received two to three months' pay as part of a separation agreement. Cain also acknowledged remembering one of the woman's accusations against him, saying he stepped close to her to make a reference to her height and told her she was the same height as his wife.
He has said he is not aware of agreements or settlements with any other women.
In media interviews since the story broke Sunday, Cain has offered conflicting accounts of what happened during his tenure at the trade group in Washington. He eventually acknowledged knowing about one settlement but said he did not know how much was paid. The New York Times reported Tuesday that one payout was $35,000, equivalent to one year's salary for one of the women.
The pressure on Cain only increased when a pillar of the GOP establishment suggested Wednesday that the Georgia businessman should ask the association to waive the confidentiality agreements. "What are the facts?" asked Mississippi Gov. Haley Barbour on MSNBC. "If you have a confidentiality agreement that keeps the public from finding out something that the public is interested in knowing the facts, you ought to go on and get the facts out."
Associated Press writers Kasie Hunt, Brett Blackledge and Mark Sherman in Washington and news researcher Judy Ausuebel in New York contributed to this report.