WASHINGTON — According to eight years of Sen. John McCain’s medical records reviewed by The Associated Press, the presumptive Republican presidential nominee appears to be cancer-free and is generally in good health.
On Friday, other news media organizations get their chance to examine McCain's medical records.
Since the start of the primary season, McCain's age, 71, and his earlier melanoma diagnosis have been the subject of great debate.
If elected, the Arizona legislator would be the oldest person to ever be inaugurated as president.
Whether age or illness will affect McCain's chances of victory in November is uncertain.
But there are historical precedents — sometimes, a candidate's health can help decide an election.
Bruise bruises Nixon campaign
Republican nominee Richard Nixon didn’t know it on that day in August of 1960, but when he whacked his kneecap on a car door in Greensboro, N.C., it may have cost him the election.
Nixon’s knee bump seemed like just an everyday bruise.
Slideshow: When illness strikes But the pain persisted and after a test for infection, his doctor called him and said, “You better get out to the hospital or you will be campaigning on one leg.”
Nixon had a staph infection. His doctor ordered him to remain in the hospital for two weeks and receive massive doses of antibiotics.
From his hospital bed Nixon watched as his opponent, Democrat John F. Kennedy, charmed the voters. The pain in Nixon’s knee was bad, but he wrote later “the mental suffering was infinitely worse.”
Other political news of note
Clinton: Mandela's example 'went way beyond political leadership'
Recalling Nelson Mandela as a “profoundly good man” and “great friend,” former President Bill Clinton said Friday that the South African leader “set an example for how to live that went way beyond political leadership to the core of what life should be about.”
- Fasting for reform: Strikers starve over immigration
- Obamas to travel to South Africa for Mandela remembrance
- First Thoughts: Universal, bipartisan praise for Mandela -- when that wasn't always the case
- Washington wasn’t always united on Mandela
- Clinton: Mandela's example 'went way beyond political leadership'
As soon he was released from the hospital, he threw himself into frenetic campaigning, became exhausted and ill and arrived in Chicago on the night of his first debate with Kennedy, as his biographer Stephen Ambrose wrote, “about ten pounds underweight, his shirt collar loose around his neck… his face wan.”
An hour before the debate when the two candidates entered the TV studio in Chicago, "It was apparent to Nixon that he had made a mistake" in agreeing to debate Kennedy, said the debate moderator Howard K. Smith in his memoirs. Nixon "was downcast; he knew it was a mistake."
Nixon decided to not wear makeup. On the television screen, he looked, according to journalist Theodore H. White in The Making of the President 1960, “tense, almost frightened, at turns glowering and occasionally haggard-looking to the point of sickness.”
Those listening to the debate on radio thought that Nixon and Kennedy had performed equally well; those watching on television deemed Kennedy the winner.
Kennedy "later told me he won the election that night," Smith wrote.
Illness can decide the outcome
Nixon’s knee illustrates how a candidate’s illnesses and injuries may help determine the outcome of an election. That truth applies both to candidates and their running mates.
Having won the 1968 election, Nixon was up for a second term in 1972.
The 1972 Democratic convention chose Sen. George McGovern as its presidential nominee and confirmed his choice of Sen. Thomas Eagleton as his running mate.
Two weeks after the convention, Eagleton told McGovern that he’d been hospitalized for “nervous exhaustion and fatigue” three times from 1960 to 1966.
The Knight newspaper chain was about to run the story, so Eagleton summoned a press conference and uttered frightening words: He’d had electric shock treatments after periods of exhaustion.
A reporter asked, “Did you find during these periods of exhaustion that it affected your ability to make rational judgments?”
No, Eagleton explained. “I was depressed. My spirits were depressed.”
Today, with ample advertising for anti-depression drugs, many Americans are familiar with depression as a condition that affects them or people they know. But in 1972, depression was more politically explosive.
McGovern’s aides had not thought to ask Eagleton during their vetting of him whether he’d been treated for depression. And Eagleton said years later that it didn't occur to him to mention his three hospitalizations to McGovern. The McGovern aides did ask if he had ever used drugs or had drunk alcohol to excess.
After the story broke, McGovern stood by Eagleton, telling reporters the Missouri senator was “fully qualified in mind, body and spirit” to “take on the presidency on a moment’s notice.” McGovern added, “I don’t have the slightest doubt about the wisdom of my judgment in selecting him as my running mate.”
Why Eagleton had to go
But after six days, McGovern decided Eagleton had to go. “Continued debate between those who oppose his candidacy and those who favor it will serve to further divide the party and the nation,” McGovern told reporters.
The Eagleton affair did nothing for McGovern's credibility, but it was only one of his many problems in the 1972 campaign. He lost to Nixon in a landslide.
After Eagleton’s death in 2007, McGovern said that he'd erred in dumping him from the ticket. "My first reaction was to say I was going to stay with him," McGovern told the AP. "But gosh, the outcry across the country was pretty intense. We felt that since we were starting a new campaign we needed to get that off the front page and we needed to get Tom to step down.”
Clark Hoyt, one of the correspondents for The Miami Herald who broke the story in 1972, wrote after Eagleton’s death, “I believe that Eagleton's mental health history was relevant to his fitness for the office he was seeking, a heartbeat away from control of the nation's military and nuclear arsenal, perhaps in a moment of international crisis."
He added, "We don't know how well Eagleton might have stood up under such stress because he never authorized any of his doctors to talk to the press or [authorized] the release of his medical records.”
While a candidate’s belated disclosure of his medical history can be disastrous, no disclosure at all sometimes has helped a candidate skate past Election Day successfully.
Kennedy's disease in 1960
At the 1960 Democratic convention in Los Angeles, Kennedy, 43, sought to portray himself as more physically fit than his rival Sen. Lyndon Johnson, 52, who’d suffered a heart attack in 1955.
In an implied contrast with both Johnson and with President Eisenhower, who himself had suffered a heart attack in 1955 and a stroke in 1957, Kennedy said the next president needed to have “the strength and health and vigor” of a young man.
In a last-ditch effort to block Kennedy from winning the nomination, two Johnson supporters called a press conference to reveal that Kennedy had long suffered from Addison’s disease, an ailment that, left untreated, could have killed him.
(One of those Johnson allies was John Connolly. In a twist of history, Connolly was in the limousine with Kennedy in Dallas on Nov. 22, 1963 and was wounded in the assassination that killed the president.)
Kennedy’s campaign manager, his brother Robert, devised a statement from his doctors which denied that Kennedy had Addison’s disease, but instead suffered only from an “adrenal insufficiency.” It was “a remarkable piece of political double talk,” said Kenneth Crispell and Carlos Gomez in their book "Hidden Illness in the White House." But it helped muffle the controversy.
Even more successful than Kennedy in 1960 in keeping his medical condition secret was President Franklin Roosevelt in 1944.
Roosevelt's ill health in 1944
A cardiologist diagnosed FDR with extreme hypertension and heart disease eight months before the 1944 election. But this was known by only a few people in the White House.
In the fall campaign, Roosevelt's Republican opponent, Gov. Thomas Dewey of New York, made jabbing references to “the tired old men” in the White House.
And voters who watched Roosevelt on newsreels at their movie theaters could see he was thin and tired, not the ebullient crusader he had been in 1940, when he won his third term. But they did not know how sick he was. Roosevelt won a fourth term on Nov. 7, 1944, and died just five months later.
In 1992, Democratic presidential contender Paul Tsongas opted for partial disclosure.
The former Massachusetts senator told voters that he had recovered from the lymphatic cancer that he’d had seven years earlier. Tsongas invited the news media to photograph him swimming laps in a pool to demonstrate his good health. He accused his rivals of “trying to spread (false) stories” about his health.
"I don't believe even if it came back it would kill me in a four-year period," he said in March of 1992, a few weeks after beating Bill Clinton in the New Hampshire primary.
Belated disclosure about Tsongas
Tsongas soon ran out of money and dropped out of the race. Shortly after his exit, his doctors admitted that he had suffered a recurrence of cancer in 1987, less than a year after undergoing a bone marrow transplant.
Tsongas had another recurrence of cancer in November 1992 and died of pneumonia on Jan. 18, 1997.
The episode raised questions: What if Tsongas had beaten Clinton in ’92 and gone on to win the presidency? How would a fatally ill president have functioned? Could he have done his job while undergoing chemotherapy?
The 25th Amendment to the Constitution, ratified in 1967, sets up a procedure for a president to temporarily step aside and have the vice president serve as acting president.
It also allows for a two-thirds vote by Congress to decide who should serve when there's a dispute between the president, on the one hand, and his vice president and cabinet officers, on the other, on whether the president is able to serve.
Reagan's mental acuity questioned
In 1984, the issue wasn't so much physical fitness as mental acuity.
At age 73, Ronald Reagan was running for a second term against Democrat Walter Mondale, a man 17 years younger than he. Reagan's mental sharpness became a concern after his answers in their first debate came across as muddled.
Two days after the debate, the Wall Street Journal reported, “Until Sunday night's debate, age hadn't been much of an issue in the election campaign. That may now be changing. The president's rambling responses and occasional apparent confusion injected an unpredictable new element into the race.”
But Reagan defused the controversy by using humor in his second debate with Mondale: “I will not make age an issue in this campaign. I am not going to exploit, for political purposes, my opponent’s youth and inexperience.”
Reagan ended up winning 49 out of 50 states.
© 2013 msnbc.com Reprints