In a country that has never seen a televised election debate before, tonight's spectacle will be, in the words of one London newspaper's front-page banner, "Ninety minutes that could change Britain."
At 8:30 tonight (3:30 EST), Gordon Brown will face his two youthful contenders for British Prime Minister, Conservative David Cameron and Liberal Democrat Nick Clegg, in the sort of face-to-face TV showdown that has become a staple in Canadian and US elections but is a complete novelty in the more personal and traditional world of British elections.
The broadcast from a Manchester hotel, the first of three debates to be held over a week, has turned into a fate-changing spectacle. Surveys suggest that about 30 million people, or 65 per cent of the voting-age population, will be watching the debate, and half said that their votes are likely to be influenced by what they see.
Almost exactly 50 years after TV debates transformed North American elections with the campaign-changing 1960 debate between Richard Nixon and John F. Kennedy, many British observers feel that tonight's showdown will mark a similarly decisive moment. The only question is who will be playing Kennedy.
An unusually larger number of voters remain undecided, meaning that the debate could produce dramatic shifts of fortune for any candidate able to score an eye-catching knockout.
For Mr. Brown, who has an awkward stage manner and a tendency to trip over his tongue and repeat staid phrases, the challenge will be to transform that into an air of seriousness and gravitas, drawing on the admiration he earned for orchestrating a global rescue from the credit crisis.
Mr. Cameron will be able to counter that with his youthful energy and rhetorical skills, but will be challenged to avoid seeming flighty and superficial, devoid of any deeper vision - - an image that has dogged him throughout the campaign and kept the Tory margin from reaching into majority-government territory.
It could be a transformative moment for Nick Clegg, leader of the perpetually third-place Liberal Democrats and a respected debater who has both the youth of Mr. Cameron (they're both 43) and the intellectual nous of Mr. Brown. He held up impressively earlier this weke in a live one-on-one grilling with Britain's notoriously brutal TV interviewer Jeremy Paxman.
Mr. Brown began the day by admitting that he was nervous, in characteristically inelegant language: "I don't think anybody goes into something new without feeling something about what's going to happen," he said, "But equally it's a chance to talk directly to the people."
His most prominent and powerful cabinet minister, the silver-tongued Peter Mandelson, set the tone more directly by telling reporters on the prime minister's campaign bus that Mr. Brown considers his Tory counterpart "a bit trivial and a bit glib."
"The public will see a smart-alec is coming towards them," Mr. Mandelson said. "That's what David Cameron has to be careful of."
Mr. Cameron, who also admitted he was nervous, surprised some by complaining about the format of the debate, which was agreed between the three parties, saying it might be "a bit slow and sluggish." In contrast to the rapid-fire format of some North American debates, there will be as few as eight questions over the 90 minutes, allowing detailed exchanges over policy.
For many Britons, the debate marks a turn to a more North American style of politics that is either refreshing or alarming, with the prospect of personal style overwhelming larger matters of policy more than before.
The Times, beneath the headline "The Screen Test," ran a huge front-page photo of Kennedy and Nixon in 1960, its story suggesting strongly that Mr. Brown's dour and plodding style could put him in the Nixon seat.
But the TV networks have been running frequent clips of the 1984 Ronald Reagan-Walter Mondale debate, in which a Republican president who had been denounced as fumbling and senescent altered the polls with a few rhetorical flourishes - something Mr. Brown could conceivably pull off.
Almost all the policy questions will involve the economy, either directly or indirectly. With a deficit of 11 per cent of the national economy and debt levels above 60 per cent of GDP, Britain will have to face a difficult period of program cuts during the next Prime Minister's term, and much of the election involves questions of how this should be handled.
Mr. Brown's promises to maintain stimulus spending for another year to promote growth before cutbacks are in sharp contrast to Mr. Cameron's calls for immediate cuts and a smaller, more localized public service.
While Mr. Brown's plans won the backing of the largest group of economists this week, Mr. Cameron will be able to point out that the worst recession of modern history unfolded under Mr. Brown's watch.
A poll by the MORI firm today showed the Tories leading Labour by 5 per cent, 35 per cent to 30 per cent, with the Liberal Democrats capturing a strong 21 per cent. Because Conservative votes tend to be clustered in strongly-held ridings, most analysts believe the party would need more than a 10 per cent lead to win the 326 seats needed for a majority, and the party has rarely broken past this threshold despite leading in every poll taken since the beginning of 2010. The debate could change those numbers dramatically.