Since the first such encounter between John Kennedy and Richard Nixon in 1960, debates have grown into a traditional highspot of every campaign: indeed, as the one chance for ordinary voters (60 or 70 million are expected to tune in tomorrow evening) to see the party nominees in a face-to-face match-up, they have acquired almost mythical status.
But for all the gaffes great and small which litter their history - from Gerald Ford's ill-judged remark about Poland being free of Soviet domination to Michael Dukakis' unhuman self-control in 1988 when replying to a question about his wife being raped and murdered - none has ever produced the complete reversal of fortunes that Mr Bush needs now.
Yesterday technicians were putting the final touches to the hall at St Louis University, where a single moderator will oversee the questioning of Mr Bush, Mr Clinton and the independent Ross Perot by a panel of three journalists. The candidates themselves have retreated into pre-combat purdah, swotting up on policy and holding mock debates, to perfect the one-liners that will dominate the next day's TV clips.
For Mr Bush, his notoriously clever Budget Director, Richard Darman, has been playing Mr Clinton, while the former Chief of Staff and hatchet-man John Sununu has been impersonating Mr Perot. A New York lawyer friend has been standing in as Mr Bush in the Arkansas Governor's preparations. Mr Clinton has also been resting his voice.
None the less, his task is infinitely easier than that of the President. Essentially, Mr Clinton goes into the debate in the same position as previous challengers like Jimmy Carter and Ronald Reagan, requiring no more than a competent performance to prove his Presidential timber and thus 'close the sale' with a not yet wholly convinced American public.
To prevent this happening, Mr Bush has precious few options and - if the barrage of attacks on the Democrat's alleged role in anti- Vietnam demonstrations and his trip to Moscow at the end of 1969 is anything to go by - his advisers have concluded the best of those options is to seek to portray his opponent as at best evasive and untrustworthy, and at worst a veritable 'Manchurian Candidate', brainwashed and pre-programmed by the KGB.
Unfortunately, the tactics may backfire. Not a shred of fact has been produced to substantiate the insinuation and innuendo. Press reaction has been uniformly scathing: 'deplorably sordid' was the phrase used yesterday by the Los Angeles Times, which reported how the onslaught was hatched in the Oval Office on Tuesday between President Bush and four Republican Congressmen who have been daily savaging Mr Clinton on the House floor. According to the paper, they told the President he could 'kill Clinton politically' by focusing on his anti-war efforts and the Moscow visit. 'In some countries,' one Congressman is quoted as saying, 'if something like this came out, he would be tried as a traitor. Tokyo Rose (a Japanese-American broadcaster who tried to persuade US troops to surrender in World War Two) had nothing over Clinton.'
More important, as poll after poll giving the Arkansas Governor a double-digit lead underlines, the electorate is far more concerned with economic misery in 1992 than what may or may not have been perpetrated by a young Rhodes Scholar 23 years ago.
And thus Mr Bush has been backing off from his most brazen insinuations. He was not challenging Mr Clinton's patriotism, he asserted on ABC TV, professing himself content with his opponent's insistence that he had gone to Moscow simply as a tourist: 'As far as I'm concerned, that ends the questioning.' As Mr Bush knows perfectly well, it will not.
The entire episode has been a case study in the two George Bushes. As President he is patrician and charming. But when in 'campaign mode'he is the candidate who famously told interviewer David Frost he would do 'what it takes' to win.
Which Bush will be on display in St Louis remains to be seen, but the omens are not promising. His performance this week has been a blend of smear and self-pity. 'This has been the worst political year I've ever seen,' Mr Bush complained in New Orleans on Thursday, 'The ugliest, the nastiest, everything goes, no accountability.' But in the next breath he makes clear he'll 'have more to say' on the allegations against Mr Clinton. So far at least, the public has not been impressed.Reuse content