John Edwards, the former Democratic presidential candidate, admitted he had an affair with film maker Rielle Hunter, who worked on his campaign back in 2006. Edwards admitted he had made a terrible mistake and explained how sorry he was for the harm he caused his wife. He confessed all these in an interview with Bob Woodruff for ABC's Nightline on Friday.

His admitting that may lead to a collapse of his political ambitions including his hope of becoming attorney-general in a Barack Obama administration.

Edwards denied having a baby with Rielle Hunter. "I am and have been willing to take any test necessary to establish the fact that I am not the father of any baby, and I am truly hopeful that a test will be done so this fact can be definitively established," Edwards said. A former Edward’s campaign staff member professes to be the father.

John Edward and his wife have three children: Cate, Jack and Emma Claire. Another son, Wade, died at 16 in a 1996 car accident.

In her statement on Friday, Elisabeth Edwards called the affair a "terrible mistake." She also added that the healing process was "oddly made somewhat easier" after her diagnosis of breast cancer in March 2007.

The National Enquirer first released the news about the affair in October 2007, in the run-up to the Democratic primaries. But Edwards denied it.

On this matter Barack Obama said: “This is a difficult and painful time to them. And I think they need to work through that process of healing. My sense is that that's going to be their top priority."

Edward told CBS that he has no plans to attend the Aug. 25-28 convention.