And in retrospect, observers might have wondered why virtually the entire senior staff of his 2004 campaign departed before the beginning of his 2006 race.
Campaign managers Scher and Nick Baldick and communications aides Jennifer Palmieri, Kim Rubey and David Ginsberg all made their excuses, but some have since told friends that they left because they were nervous about Hunter.
Some of them now blame those who stayed for "enabling" Edwards' run, as one put it. Others say aides had little choice but to dismiss the rumors, and they point to other reasons for departures, noting that former staffers such as Baldick had clashed with Elizabeth Edwards, whose central role in her husband's public life was a consistent source of internal tension.
And so some top advisers, such as pollster Harrison Hickman, chose to stay.
"I asked him. He told me they weren't true," one former senior aide said of the rumors. "What are you supposed to do? Say, 'I think you're a liar. I refuse to do my job'?
"If you had to quit every time there was a rumor that a politician was being inappropriate with regard to sex, nobody would work in politics," the aide said, speaking - like almost all of Edwards' former staffers - on the condition of anonymity, because few have any interest in being dragged back into a damaging scandal.
The departure of Edwards' inner circle also didn't scare off prominent supporters such as former Michigan Congressman David Bonior and labor leaders Bruce Raynor and Leo Gerard. Soon they were joined by a new cadre of devoted young staffers and political pros like consultant Joe Trippi, who later told associates they had no idea of the gathering storm. Prominent Democrats also threw themselves into the campaign.
Trial lawyer Fred Baron, Edwards' friend, provided a private jet that saved Edwards' campaign many thousands of dollars, and he was a regular presence at headquarters, buying staffers drinks and dinner. Though Baron would die of cancer before the end of the campaign, senior aides never knew he was sick.
Elizabeth Edwards' cancer, though, was a very public struggle. In March, she announced it had recurred but did not take the opportunity to end her husband's campaign, standing beside him to urge him ahead.
"John was much more reluctant to continue the campaign than she was," said a former aide who was present as they made their decision.
In late August or early September, the campaign's press office took a call from a reporter for the National Enquirer. Instead of scuttling the campaign, it launched another intense - and largely successful - round of denials.
The concerted effort to keep the Enquirer story from reaching the average Iowa Caucus-goer was, a former top aide said, "a campaign within a campaign." Even Edwards' new top strategist, Trippi, was left off the first of the conference calls on the subject, which included some members of the candidate's 2004 circle who had taken a pass on the race, as well as aides who had stayed in 2006.
The aides ran a full-court press on reporters who asked about the Enquirer piece, asking them if they really planned to follow a supermarket tabloid and saying - accurately - that evidence of an affair was thin.
For those who suspected the story was true, the real point of the effort was to prevent Elizabeth Edwards and their children from having to read about the candidate's infidelities in the newspapers, one campaign isider said, but the effect was to keep Edwards' shot at the White House alive.
The most forceful denial, though, was his wife's sheer presence.
"Obviously Mrs. Edwards was on the trail a lot, and people saw her and talked to her," said Jeff Link, a veteran Iowa operative who sided with Edwards in the caucuses. "That kept things from ramping up in terms of suspicion or questioning."
When the truth of the Enquirer reports became obvious, Bonior, former supporters said, spoke for many when he said Edwards had "betrayed" his backers.
Now former supporters view Elizabeth Edwards' book tour with ambivalence, sympathizing with what she describes in the subtitle as facing the "burdens and gifts of life's adversities" but wishing the campaign had never been run.
One friend described herself as "haunted" by the couple's decisions.
And even the confessional book and a federal investigation haven't yet solved the remaining mystery of John Edwards' affair. His mistress, Hunter, bore a daughter, Frances Quinn Hunter, on Feb. 27, 2008, in Santa Barbara, Calif. The line on the birth certificate for the father's name was reportedly left blank.
The former presidential candidate, in his first interview on the subject, denied the child was his and claimed the father was Andrew Young, a longtime close aide. Admitting paternity would have been conceding that his affair had resumed in spring 2007, after his partial confession to his wife.
John Edwards has not given a clear response to that question of timing, and his wife doesn't address it in her new book.
Asked by Winfrey whether her husband was the child's father, though, Elizabeth Edwards suggested the affair may have resumed.
"I have no idea," she said. "It doesn't look like my children."
By Ben Smith