WASHINGTON --- John McCain knows what hopelessness feels like.

He attempted suicide as a Vietnam prisoner of war. His young political career took a head-on blow in the Keating Five scandal. He's gone three rounds with melanoma. His quest of the presidency has been pronounced dead more than once.

Hopelessness, Mr. McCain says on the campaign trail, is "an enemy who defeats your will."

"I felt those things once before," he says of his years in Vietnam. "I will never let them in again."

And so it is that Mr. McCain, at 72, fights on, a battle-scarred warrior. His refusal to quit, his willingness to stand up against the tide, his ability to come back against seemingly insurmountable odds, are the hallmarks of a lifetime in war and politics.

But Mr. McCain knows all too well that a fighting spirit might not be enough this time.

Two weeks out from the election, he allowed a moment of reflection about "a life that's been blessed" when asked about the possibility that he could lose.

"Look, I've had a wonderful life," he said. "I'm the most fortunate man on earth."

SO MUCH OF Mr. McCain's identity revolves around his history as a prisoner of war that it is easy to overlook all that came before.

And there was a lot -- "a whole life," in Mr. McCain's own words.

By the time he was shot out of the sky over Vietnam at age 31, he'd already crashed a plane into Corpus Christi Bay, ejected from a jet that flamed out as he was flying solo, survived an explosion aboard the carrier Forrestal that left 134 dead, and generally lived large, as he once said of his grandfather.

He'd been poised to fly into combat from the deck of the USS Enterprise during the Cuban Missile Crisis. He'd knocked down power lines flying too low over southern Spain. He'd romanced a Brazilian fashion model in Rio. He'd married a beautiful divorcÃe, adopted the former model's two boys and had a daughter with her.

A predilection for what Mr. McCain describes as "quick tempers, adventurous spirits, and love for the country's uniform" was encoded in the family DNA. His father and grandfather, the Navy's first father-and-son set of four-star admirals, had set such a low standard for good behavior at the Naval Academy that John Sidney McCain III's self-described "four-year course of insubordination and rebellion" got little more than a yawn from his family.

TUCKED AWAY IN A CORNER of Mr. McCain's Senate office, there is a yellowed, three-page telegram hanging in a simple black frame.

The once-secret cable recounts a conversation at the Paris Peace Talks between the top negotiators for the United States and North Vietnam.

In it, Averell Harriman, the U.S. negotiator, reports: "At tea break Le Duc Tho mentioned that DRV had intended to release Admiral McCain's son as one of the three pilots freed recently, but he had refused."

The cable was written in September 1968. It would be four and half more years before "Admiral McCain's son" came home.

His captors had hoped to use early release of Mr. McCain -- whose father was soon to become commander of U.S. forces in the Pacific -- as a propaganda ploy. When Mr. McCain refused to play along, they told him: "Now it will be very bad for you, Mac Kane." And they were true to their word.

Mr. McCain returned home from his 51/2 years as a POW on crutches and unable to lift his arms. He still can't raise them above his head.

"He had to carry a different burden than most of us and he handled it beautifully," says Orson Swindle, a former POW cellmate who remains a close friend. "He didn't need any coping mechanism; that's just built into him."

Even in prison, Mr. McCain played to the bleachers, shouting obscenities at his captors loudly enough to bolster the spirits of fellow captives. Appointed by the POWs to act as camp "entertainment officer," a "room chaplain" and a "communications officer," Mr. McCain imparted comic relief, literary tutorials, news of the day, even religious sustenance.

Mr. McCain tells AP that Vietnam "wasn't a turning point in me as to what type of person I am, but it was a bit of a turning point in me appreciating the value of serving a cause greater than your self-interest."

It taught him, he says, "that if you put your country first, that everything will be OK."

THE CHOICES IN LIFE, the friends and the enemies, would rarely be as black-and-white again as they had been for Mr. McCain in prison.

Mr. McCain's experience there gave him new confidence in himself and his judgment. But it did not tame his wild side, and his marriage was a casualty. Mr. McCain blames the failure of the marriage on "my own selfishness and immaturity" and has called it "my greatest moral failing."

One month after divorcing his first wife, Carol, he married Cindy Hensley, 17 years his junior.

Mr. McCain's war story had made him a celebrity in Washington. When he became the Navy's liaison to the Senate, he quickly established friendships with some of the younger senators, who would stop by his office and chew over the events of the day. The experience opened Mr. McCain's eyes to the impact politicians could have, and to the notion that he could be one of them.

His 1981 marriage to Cindy, the daughter of a wealthy beer distributor in Arizona, helped clear the path forward. In one day, Mr. McCain signed his Navy discharge papers and flew West with his new wife to his new life. By 1982, he'd been elected to the House and four years later to an open Senate seat. He and Cindy would have four children. Their youngest was adopted from Mother Teresa's orphanage in Bangladesh.

Mr. McCain set about establishing a conservative voting record and a reputation as a tightwad with taxpayer dollars. But just months into his Senate career, he made what he's called "the worst mistake of his life." He participated in two meetings with banking regulators on behalf of Charles Keating, a friend, campaign contributor, constituent and savings and loan financier who was later convicted of securities fraud.

As the S&L industry collapsed, Mr. McCain was tagged as one of the Keating Five -- five senators who, to varying degrees, were accused of trying to get regulators to ease up on Mr. Keating. Mr. McCain was cited for a lesser role than the others by the Senate Ethics Committee, which faulted his "poor judgment."

To have his honor questioned, he said, was in some ways worse than what he endured in Vietnam. "It had an indelible impression on him," said former Sen. Warren Rudman, who sat on the Ethics Committee. "It was an assault on his integrity."

MR. MCCain loves the naval expression to "keep a steady strain" on the lines between ships. It's his way of telling aides and supporters not to get too cocky in the good times, too low when times are tough. He's seen it all come together -- and apart -- more than once.

His upstart bid for the presidency in 2000 took flight in New Hampshire only to get flattened by an ugly whisper campaign against his family in South Carolina. He settled back into Senate business, helping create the Gang of 14 senators, Republicans and Democrats, who pulled the Senate back from the brink of a disastrous blowup over judicial nominations.

Mrs. McCain says his desire to be president never really went away, but he bided his time through nearly eight years of George Bush.

"He always said if the opportunity arises again, 'I would love to try it again,'" she said. "But it wasn't like a dream he couldn't live without."