from www.nydailynews.com – Former presidential candidate John Edwards is out of luck if he hoped that the extramarital affairs of Gov. Mark Sanford and Sen. John Ensign would take people’s minds off his own cheating scandal.

Former Edwards aide Andrew Young says the ex-senator and his former mistress, Rielle Hunter, once made a sex tape, according to someone who has seen Young’s book proposal.

St. Martin’s Press just inked a deal with Young, who also says in his proposal that, contrary to his public statement last year, he is not the father of Hunter’s infant daughter — Edwards is. Edwards has denied that.

Young says that his belief in Edwards ran so deep that he agreed to take the fall for the candidate, inviting the pregnant Hunter to live with him, his wife, Cheri, and their three children. Later, after Hunter delivered the baby, Young and his family moved to a different home in California.

While he was unpacking, Young discovered a videocassette, according to the book pitch. Hunter had been hired by the Edwards campaign to videotape the candidate’s movements, but this one is said to have shown him taking positions that weren’t on his official platform.

The purported sex tape confirmed to Hunter that Edwards was even more reckless than he thought.

According to our source, Hunter confided to Young that she and Edwards talked about getting married should the candidate’s cancer-stricken wife, Elizabeth, pass away, even discussing what music they’d play at their wedding.

Elizabeth Edwards is said to hold Young partly to blame for her husband’s affair, since Young knew it was going on and sometimes used his cell phone to conference the senator and his girlfriend. Young has told friends that, in revenge, Elizabeth arranged for the media to learn about a youthful misdeameanor in which Young was arrested for stealing a sign from a biker bar.

Elizabeth also suspects Young stole the baseball card collection of her late son, Wade, according to a source who says that she told Young in an e-mail that other former staff members “have passed lie detector tests.”

Young’s proposal, which one editor said “was impossible to put down,” also contends that Sen. Edwards frequently clashed with running mate John Kerry during their 2004 race for the White House. And before Edwards owned up to his affair with Hunter, Young says he told him that Barack Obama had promised he’d make him attorney general if he didn’t pick him as his 2008 running mate.

Elizabeth Edwards and Young’s agent had no comment. An e-mail to John Edwards’ assistant wasn’t returned. Hunter couldn’t be reached.