Republican frontrunner changes version of events for second time in 24 hours as criticism grows over his handling of crisis

Republican presidential candidate Herman Cain was struggling to maintain a credible response to allegations of sexual harassment as he shifted his version of events for the second time in 24 hours.

After insisting on Monday that he had no recollection of any settlements being paid to two women who complained about his conduct when he was president of the National Restaurant Association, Cain changed his story on Monday night when he said he could, in fact, recall such a payout.

He also recalled that he had compared one of the women in height to his wife, and raised his hand to his chin to demonstrate his wife's height. The woman was apparently uncomfortable with the gesture, though Cain said his office door had been open and an assistant had been sitting outside.

On Tuesday morning, he added a new twist, admitting that there had been "a couple of other things" in the complaint he had not previously mentioned. He dismissed these as "ridiculous", but declined to elaborate on what they were, saying he could not remember.

In an interview with Robin Meade on the HLN programme, part of the CNN network, Cain went further, saying the complaint concerned "the gesture with the height thing, and there were a couple of other things in there that I found absolutely ridiculous".

Asked what these were, he said: "I don't even remember. They were so ridiculous, I don't remember what they are."

Meade asked him: "You remember they were ridiculous, but you don't remember what the other things were?"

Cain responded: "The reason I forgot them is because they were ridiculous. I dismissed them out of my mind. I said if she can make that stick and call that sexual harassment, fine. But it didn't stick, OK? So I don't remember what they were. The only thing that I remember is the one gesture that I made, talking about the height."

Cain, one of the frontrunners in the race for the Republican nomination to take on Barack Obama for the White House next year, claimed he is a victim of a "smear campaign".

Cain only acknowledges one incident, in 1999, when he and the woman who made the complaint worked at the National Restaurant Association. He claims to be unaware of a complaint from a second woman reported by Politico, which first broke the story on Sunday.

Although some Republicans rallied behind him, others were critical of his handling of a crisis that is in danger of consuming his campaign. The steady drip of new details and his contradictory statements could erode his support.

While no polls have yet been published since the allegations first surfaced, there are signs of a backlash beginning to build. On a CNN website following the latest interview, some continued to express support, but other respondents used words like "creep" and described him as "squirming", questioned whether he was telling the truth and asked why he had trouble remembering such a devastating event.

Early on Monday, he said that there had been no financial settlement of the complaint. But by Monday evening, he admitted there had been. Attempting to reconcile the discrepancy, he told Meade that settlement had legal implications whereas it had been a "separation agreement".

Cain, after a series of interviews on Monday and Tuesday morning, is hoping for a lull. But he has various political events lined up for later in the week, including a high-profile speech at a large gathering of mainly Republicans in Washington at the end of the week.

A Republican strategist, Charlie Black, told Reuters that Cain needed to tell a straight story with as many facts as he could muster. "For any high-profile candidate suffering under such an accusation, whatever facts there are that are known to the candidate should all be known immediately. That's not the way he's handled it so far," Black said.

If Cain's support begins to evaporate, the question is which of the other candidates would benefit. A member of Texas governor Rick Perry's campaign team said Cain had taken many supporters from Perry, but he did not know if these supporters would return to the governor.