Democrat John F Kennedy v Republican Richard Nixon
Historians believe this very first televised debate on September 26, 1960, seen by 66 million viewers, helped to clinch the presidency for the young Kennedy. Nixon, pale and unshaven, had been out of hospital for only two weeks after being treated for a knee injury. He had lost weight because of flu, and he refused to wear make-up under the studio lights. Kennedy, meanwhile, tanned after campaigning in California, looked rested and relaxed. He wore a dark suit, which stood out from the background, unlike Nixon's grey jacket. And when Kennedy answered the questions he looked directly into the camera and not at the journalist, as Nixon did.
Result Kennedy was elected.
Democrat Jimmy Carter v Republican Gerald Ford
The September 23 debate was the first held after the 1960 debut. Scarred by that early experience, Nixon refused to take part in any televised debate in 1968 and 1972. Kennedy's successor Lyndon Johnson also rejected a debate with his Republican rival in 1964. The decisive moment came during the second Carter-Ford debate when Ford, the sitting president, made an irreparable gaffe when asked about the Soviet Union's influence on Europe."There is no Soviet domination of Eastern Europe," he insisted.
Result Carter was elected.
Carter v Republican Ronald Reagan
Reagan, a former Hollywood star, revelled in his talent for public speaking during the only debate between the two candidates, just one week before the election. Speaking directly to the cameras, he asked voters that when they were about to cast their ballot: "It might be well if you would ask yourself, are you better off than you were four years ago?"
Result Reagan was elected.
Reagan v Democrat Walter Mondale
Reagan was 73, but in his second debate with Mondale, on October 21, he turned this apparent handicap into an asset. "I will not make age an issue of this campaign," he said. "I am not going to exploit for political purposes my opponent's youth and inexperience."
Result Reagan was re-elected.
Republican George HW Bush v Democrat Bill Clinton
For the first time, three presidential candidates shared the stage, including independent Ross Perot. He sought to deflate the pompous, officious style of past presidents. "Experience?" he replied when Mr Bush asked him about his candidacy. "I don't have any experience in running up a $4 trillion debt. I don't have any experience in gridlock government where nobody takes responsibility for anything and everybody blames everybody else ... but I do have a lot of experience in getting things done." Also at one point, as the candidates were asked about US economic problems, the camera caught Mr Bush looking at his watch.
Result Clinton was elected.
Republican George W Bush v Democrat Al Gore
Viewers were turned off by Mr Gore's slightly patronising air during their first debate on October 3. He also sighed loudly every time he found one of his opponent's answers unsatisfactory. By their second debate, the two men managed to agree so often on their positions that the moderator asked them to outline their differences. Mr Bush assured viewers: "I don't want to be the world's policeman. If we're an arrogant nation, they'll resent us; if we're a humble nation, but strong, they'll welcome us."
Result Bush was elected.
Bush v Democrat John Kerry
The two men held three often-intense debates. "The president didn't find weapons of mass destruction in Iraq, so he's really turned his campaign into a weapon of mass deception," Kerry said. But what everyone remembers is the mysterious bulge in Bush's jacket, which sparked a flurry of rumours that it hid some kind of listening device through which the president was being fed the answers.
Result Bush was re-elected.