WASHINGTON -- Fifty-two years ago, during the first televised U.S. presidential debate, an ailing Richard Nixon perspired so profusely it was thought to have played a role in his defeat to John F. Kennedy.
Ever since then, presidential debates have been must-see TV in America, earning their way into political folklore thanks to a legendary zinger, a spectacular gaffe or just an all-round abysmal showing.
U.S. President Barack Obama and Mitt Romney, his Republican rival, will likely create a bit of their own drama tonight in Denver, when they go head to head in the first of three debates leading up to the Nov. 6 election.
Conventional political wisdom suggests hotly anticipated debates can often change an election campaign.
Nixon was apparently so mindful of his 1960 meltdown that he refused to participate in a debate against Hubert Humphrey in 1968; he ended up winning the election by a razor-thin margin. In '72, he wouldn't debate George McGovern; Nixon trounced the Democrat anyway.
Lyndon Johnson, well aware of his oratorical shortcomings, also opted against a debate in 1964, and went on to crush Barry Goldwater.
In the nine sets of presidential debates that have been held since 1960, polling giant Gallup has found only a handful of them had a significant impact heading into election day.
The pollster pored over its results for the last half-century, and determined that only twice did the candidate trailing the front-runner surge from behind post-debate to win the election -- JFK in 1960, and George W. Bush in 2000.
"The debates were less likely to be catalyst events in years when one candidate was a strong front-runner," wrote a Gallup analyst.
That's not great news for Romney, who's hoping to turn around his struggling campaign with just five weeks until election day. Obama recently edged past him in most polls, particularly in key swing states. Some of Romney's biggest donors are reportedly pulling away, opting to invest in congressional candidates instead.
But one debate expert believes even if the verbal sparring matches don't dramatically swing polls, they're significant nonetheless.
"It's true that voters often watch them with their minds made up and tend to hear what they want to hear," said Allan Louden, a politics professor at Wake Forest University in Winston-Salem, N.C. "But they change elections anyway, because they tend to define the ongoing narratives. We have a notion that Romney is out of touch and the debate may affirm to us that he is; we hear that Obama is professorial and aloof, and we may see that indeed he is. Debates are terribly important because of their confirmation or denial of the growing narrative."
The media climate is also far different now than it was even four years ago, thanks in part to the explosion of Twitter among journalists and commentators. A gaffe can quickly take on a life of its own on the social-media platform, becoming fodder for 140-character ridicule that endures for days or weeks.
Two cases in point are Clint Eastwood's chat with an empty chair at the Republican National Convention, and Texas Gov. Rick Perry's "oops" moment during a primary season showdown. Perry never recovered from his inability to remember the three federal government agencies he was proposing to cut if elected president.
"There was a time period when campaigns had a spin room and could influence the conversation about a debate -- that doesn't work anymore," Louden said.
Even in 2000, he noted, it was a political blogger who kept hammering away at Al Gore's exaggerated sighs in a debate with George W. Bush. The story caught on and contributed to negative perceptions Gore was condescending and petulant.
"The polls may not move much but the storyline can be set and cast in stone following debates," he said.
They also create lasting memories.
In 1992, George H. W. Bush's glance at his watch when asked by an audience member how he'd been personally affected by the economic recession didn't do his presidential campaign any favours. It exposed a contrast between the incumbent and Bill Clinton, a folksy politician who answered with far more empathy.
Obama's team wants its man to deliver short, pithy answers and to avoid bristling with impatience at either the moderator or Romney. Those guiding Romney want to ensure he stays calm and presidential, mindful of the occasional flashes of anger he displayed during primary season showdowns.
-- The Canadian Press