Former US Democratic presidential candidate John Edwards on Friday admitted that he had an extramarital affair in 2006 with a woman he met in a New York City bar.
He confessed to the affair in an interview with ABC News.
In a statement issued following his television appearance, Mr Edwards said he had made "a serious error in judgment". He said he was "ashamed" of his actions.
The admission followed reports of the sex scandal in the National Enquirer newspaper, which he had dismissed as "tabloid trash".
Mr Edwards, 55, said he had told his wife Elizabeth that he had a liaison with another woman and had asked for her forgiveness.
Mrs Edwards has incurable cancer.
Before Friday's disclosure, there had been speculation that Mr Edwards might be a vice presidential running mate for Democratic candidate Barack Obama or be appointed to Mr Obama's Cabinet if he won the White House.
Mrs Edwards has posted her own thoughts to a diary she keeps on a news blog, Daily Kos. She said she considered the affair a private matter.