Edwards told ABC News that he lied repeatedly about the affair with a 42-year-old woman but said that he didn't love her. He said he has not taken a paternity test but knows he isn't the father because of the timing of the affair and the birth.
ABC said a former Edwards campaign staffer claims he is the father, not Edwards.
In 2006, Edwards' political action committee paid $100,000 in a four-month span to a newly formed firm run by Rielle Hunter, who directed the production of just four Web videos, one a mere 2 1/2 minutes long.
Hunter's daughter, Frances Quinn Hunter, was born on Feb. 27, 2008, and no father's name is given on the birth certificate filed in California.
Edwards was a top contender for the Democratic nomination for president. He placed second in the Iowa caucuses last January but dropped out of the race a few weeks later.
Edwards, a former senator from North Carolina, was the Democratic nominee for vice president in 2004.