WASHINGTON — If the case against former presidential candidate John Edwards goes to trial, prosecutors plan to use his own emails with a former aide to help prove a key element of their case against him.

People familiar with the case told The Associated Press that Edwards and his former speechwriter Wendy Button exchanged emails working on a draft statement for him to acknowledge what he had denied publicly — paternity of his out-of-wedlock child, along with knowledge of payments to keep his pregnant mistress in hiding.

The messages, draft statements and notes of their related phone conversations were obtained by prosecutors in their case against Edwards, indicted on charges he failed to report nearly $1 million allegedly spent to keep his mistress out of the public eye as he pursued the White House. The former senator was still denying he was the baby's father and publicly maintained he knew nothing about any money that may have been spent when the emails were sent in summer 2009.

Prosecutors must prove the 2004 vice presidential nominee had knowledge of the payments to convict him in the campaign finance case. Edwards proclaimed his innocence of any crime after being indicted Friday.

His attorneys declined to comment on the evidence revealed to the AP.

The six felony charges came after intense negotiations in which prosecutors first insisted Edwards plead to a felony before ultimately offering him the chance to plead guilty to misdemeanor charges and serve a jail sentence, according to people with knowledge of the talks who requested anonymity to discuss the private discussions. Edwards, a single father since his estranged wife's death in December, was interested in reaching a deal but refused to accept anything that would take him away from his children, according to a person close to the talks. By definition, a misdemeanor could carry jail time of no more than one year.

During the talks, prosecutors presented their evidence to Edwards to encourage him to take a deal. A person who has seen the emails described the following context:

Button worked on the 2004 Edwards presidential campaign, continued to write his speeches between his two White House bids and was brought on to help with some drafts toward the end of the 2008 campaign. She reached out to her former boss in July 2009, when he had yet to admit he fathered a child with his former videographer, Rielle Hunter.

The presidential race was long over by then, but the reports continued to dog Edwards. News media reported that Edwards' former aide Andrew Young was writing a book about how he falsely claimed paternity of the child at Edwards' request. Edwards' former campaign finance chairman Fred Baron had come out a year earlier to admit that he sent Young and Hunter money to keep them out of the media, but claimed Edwards hadn't known about the payments.

Button emailed Edwards urging him to admit paternity so he could move on with his life. She acknowledged not knowing all the facts, according to email prosecutors have obtained. But she suspected a cover-up and attached a draft statement for him to consider in which he would admit being father of the child, Frances Quinn Hunter, and apologize to Young and Baron.

Edwards responded by asking her to call him, and in their phone call he admitted he was the father and said they should craft a statement together that told the truth, according to notes of the call Button took to guide her drafts. But he insisted she take out any apology to Young because of bad blood between the two, according to the notes now in the hands of prosecutors.

During this time, news media reported that Edwards and Hunter made a sex tape. Edwards told Button he wanted to come clean about it all, including the sex tape and the payments from Baron, according the notes the prosecutors have. The notes say Edwards told Button he knew Baron had been sending money to support Hunter, even though Edwards said he never asked for a dime.

That could help Edwards' defense because it contradicts the indictment's allegation that Edwards was part of a conspiracy to solicit the funds. On the other hand, Young has said he and Edwards discussed who would pay to keep his mistress on the run — a key point in the indictment.

Button was interviewed by investigators after she and many other former Edwards aides were subpoenaed to turn over all relevant documents, the person involved said. Button's notes are quoted in the indictment, which doesn't name her but refers to her as a former campaign employee in describing their discussions about Baron's money.

"Edwards further told the employee that this was a huge issue and that for 'legal and practical reasons' it should not be mentioned in the statement they were preparing," the indictment said. But the statement they worked on was never released, and Edwards didn't admit paternity until the following year as Young's book was about to be published.

Justice Department spokeswoman Laura Sweeney declined to comment on the pending matter.

Button wrote about her discussions with Edwards over the draft statement in a Huffington Post article in February 2010, shortly after Edwards finally admitted fathering Frances Quinn in a statement very different from what they worked on.

"From early July until the end of August 2009, we spoke frequently and worked on words," Button wrote. "He told me that he had told the rest of his family the truth and that Elizabeth was against him going public. Every time he made a case or another's case about not telling the truth, my argument was always the same. 'You need to tell the truth. You denied a child in public. You have to embrace her in public. Children need to see their parents do the right thing, even if it is painful. You have to apologize for what you did during the campaign and after. You hurt a lot of people. This is the right thing to do.'"

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