Republican Herman Cain has denounced sexual harassment accusations from the 1990s as a "witch hunt" and broke into a gospel song to deflect what has become the toughest challenge of his US presidential campaign.
The report, which came with Cain riding high in the polls, could damage his surprisingly strong bid to be the Republican challenger to Democratic President Barack Obama in the November 2012 election.
Cain acknowledged that he was accused of sexual harassment while heading the National Restaurant Association but declared an internal investigation had cleared him of the allegations.
News website Politico reported late yesterday that two women employees complained of sexually suggestive comments and gestures by Cain at the association.
Cain said that when the allegations arose, he contacted the firm's general counsellor and human resources official conducted an investigation that concluded the charges "had no basis."
Cain, 65, has been an unlikely front-runner, competing with former Massachusetts Governor Mitt Romney for the lead in polls of Republican voters with two months until primary elections start to choose the party's 2012 presidential nominee.
The allegations could be critical in Iowa, where evangelical conservatives are a dominant voice and where Cain holds a narrow lead in the polls ahead of the state's 3 January caucuses, the country's first 2012 nominating contest.
Republicans have struggled to find a front-runner with conservatives seeking an alternative to the more moderate Romney. Minnesota Congresswoman Michele Bachmann, Texas Governor Rick Perry and now Cain have attempted to fill that role.
