Today John Edwards admitted his affair with a filmmaker who (later?) worked for his campaign making commercials.
Edwards' wife Elizabeth's cancer was a significant issue in the campaign and this indiscretion is magnified by the fact that many who admired the courageousness of her campaigning in the midst of a cancer battle will be particularly upset by Edwards' infidelity. Of course campaigns, sex, lies, and videotape are all intertwined in complex ways in American politics so it is possible this matter was already known to Elizabeth, as Bill Clinton's many dalliances were well known to Hillary even as she helped him imply there was little or no foundation to the rumors.
This unsavory story certainly destroys any chance Edwards has of becoming Obama's VP.
Fair or not, stories like this are political suicide.