CHAPEL HILL, N.C. -- John Edwards on Thursday stood beside his wife, Elizabeth, at the site of their wedding reception 30 years ago and said some of the most painful words a human being can utter: "Her cancer is back."

With that, the 2008 presidential campaign entered uncharted territory: A leading candidate will continue to live the public life of trying to win the White House while enduring the personal ordeal of watching his wife battle a deadly disease.

Thursday's announcement, at an inn near the campus where the couple met as law students, provided a glimpse of complex emotions while sparking a national debate over whether the couple should focus their energy on fighting the disease or remain in a grueling, around-the-clock campaign that can exhaust even the healthiest participants.

The Edwardses -- who were upbeat during their news conference but choked up at points -- surprised many people when they announced that his campaign for the Democratic presidential nomination was not over.

"It goes on strongly," the former senator from North Carolina said. "From our perspective, other than sitting around feeling sorry for ourselves, there was no reason to stop."

The couple tried to strike an optimistic tone, even while revealing that Elizabeth Edwards' cancer -- first diagnosed in 2004 -- had spread from the breast into her bone, indicating that it was no longer curable. "Elizabeth will have this as long as she is alive," John Edwards said.

But, he said, the illness is treatable. "And many patients in similar circumstances have lived many years undergoing treatment," he said.

Many in the political world -- and in the large community of people whose lives have been touched by cancer -- responded with an outpouring of emotion.

Laura Farmer, a breast cancer survivor, said she wept while watching the televised news conference from her office in San Diego. "She's a role model for coping," said Farmer, a spokeswoman for Susan G. Komen for the Cure, a breast cancer foundation.

Andrew Sullivan, a conservative political commentator with HIV, wrote on his blog: "What I saw in this press conference was the reality of family values -- not the rhetoric, not the divisiveness, not the politics, just the reality of an actual family dealing with real issues."

As a practical matter, the announcement guarantees that Edwards' campaign will receive far more attention in the coming days than it has of late, as he has labored in the shadow of Sens. Hillary Rodham Clinton and Barack Obama.

The campaign sent out an e-mail Thursday afternoon indicating the couple still planned to attend a fundraiser tonight in Los Angeles. The candidate also was expected to stick to plans to attend two fundraisers Monday in the San Francisco Bay Area.

But the long-term political implications are uncertain. His wife's illness may engender sympathy and add an element of human interest to Edwards' campaign. But there is a risk: Some voters may regard his presidential bid as a misplaced priority, especially if his wife's condition deteriorates.

Democratic pollster Peter Hart said Edwards would have to strike a "delicate balance ... between a loving husband and an ambitious politician."

What's more, Edwards' campaign will be colored by the progress of his wife's disease. Having promised Thursday to be with her "anytime, anyplace" that she needs him, Edwards may have to make long detours home from the campaign trail.

Rep. Lois Capps (D-Santa Barbara), whose daughter died of lung cancer seven years ago, said she was surprised to hear Edwards say he would continue to campaign. But she likened his decision to her own decision to pour herself into legislative work after her daughter's death.

"You retreat or get going with renewed vigor," Capps said. "I decided to roll up my sleeves."

Though Edwards is not the first politician to cope with a loved one's grave illness, Thursday's announcement marked novel territory for presidential candidates, who already put severe strains on family life -- and on their own health -- by deciding to run.

One Edwards strategist, Dave "Mudcat" Saunders, said the couple's news motivated him to work harder. "Suddenly I went from 80 miles per hour to 200 miles per hour," Saunders said.