Indian-American Nikki Haley's bid for the governorship of South Carolina has been marred by allegations that she had an extra-marital affair with a conservative blogger, a charge refuted by the Republican candidate.
Haley, who is a current member of the South Carolina House of Representatives, is strongly backed by Republican heavyweight Sarah Palin, who was the Vice Presidential candidate in the 2008 Presidential elections.
Haley's parents hail from Amritsar in Punjab and they migrated to the US decades back.
Endorsed by Palin, also the former Alaska Governor, and top Republican leader Mitt Romney, Haley surged ahead of several of her Republican rivals in the latest series of opinion polls.
The 38-year-old mother of two, whose husband is a US Army reserves officer, has been hit by allegations that she had a "physical" relationship with commentator Will Folks.
The claims are threatening to derail her campaign to replace the disgraced former governor Mark Sanford, who fell from grace after he was forced to admit of having an affair.
If elected, she would be only the second governor of Indian origin in the US after Louisiana's Bobby Jindal.
"I have been 100 per cent faithful to my husband throughout our 13 years of marriage. This claim against me is categorically and totally false. It is quite simply South Carolina politics at its worst," Haley said.
"This disgraceful smear has taken form less than a week after being removed from the release of a poll showing our campaign with a significant lead," she said in a statement.
The controversy erupted when Folks posted a statement on his website claiming that "several years ago, prior to my marriage, I had an inappropriate physical relationship with Nikki. That's it".
Since then Folks has posted about a dozen posts on his websites, but has not been able to provide any proof in support of his claims.
Meanwhile, Palin has come out in defence of Haley, saying allegations of extramarital affairs against the gubernatorial aspirant are completely false.
"South Carolina: Don't let some blogger make any accusation against your Nikki if the guy doesn't even have the guts or the integrity to speak further on such a significant claim," Palin wrote in a posting on her Facebook page.