Rupert Cornwell: Feisty underdog must now watch his temper

Just possibly, there is only one thing standing between John McCain and his party's nomination – the Arizona senator's sneering ill temper so evident in his exchanges with his main rival Mitt Romney at the latest Republican candidates' debate.

The debate, held on the hallowed ground of Ronald Reagan's presidential library in California, of itself settled nothing. But suddenly the pieces in the puzzle seem to be falling into place for Mr McCain, in the run-up to Tuesday's make-or-break primaries and caucuses in more than 20 states.

The turn-around is remarkable for a campaign that just six months ago was on life support, bereft of money, written off by most of the media and abandoned by several top advisers. Today, though his lead in committed delegates is small, Mr McCain is clear favourite to be the Republican standardbearer in November, as even a party establishment long suspicious of him extends a wary embrace.

That shift was underlined by his back-to-back wins in the two traditionally Republican states of South Carolina and Florida, where the backing of top elected Republicans helped secure his narrow victories. The success in Florida – in a primary that excluded independents who usually flock to Mr McCain's banner – was especially telling.

Endorsements of course are probably not all they are cracked up to be. But the Arizona senator could not have wished for two weightier and better-timed ones than those bestowed upon him in the past couple of days from the former New York mayor Rudy Giuliani and Governor of California Arnold Schwarzenegger.

If that were not enough, the former Arkansas governor Mike Huckabee is staying in the race, without the money and cross-party appeal to have a serious chance of the nomination, but still attracting a significant number of conservative votes that might otherwise go to Mr Romney.

The Huckabee effect may well have handed victory to Mr McCain in Florida, where the former won 13 per cent of the vote, more than double Mr McCain's winning margin of 5 per cent. The pattern could be repeated in other southern and Midwestern states such as Georgia, Tennessee and Missouri next Tuesday.

The monetary edge still lies with Mr Romney. Mr McCain is still being forced to interrupt his campaigning for fund raisers – but not the former Massachusetts governor and businessman, with his huge personal fortune.

Mr Romney will also draw comfort from the fact that most primaries from now on are limited to registered Republicans only, meaning that independents cannot take part. Mr McCain overcame that handicap in Florida, but it may have an impact in California and elsewhere on Tuesday.

The mutual dislike between McCain and Mr Romney has long been evident, but never as visibly as at the Reagan Library. "Thou shalt not speak ill of a fellow Republican" was the proclaimed "11th commandment" of the patron saint of modern Republicanism. But that precept went by the board in the heated and testy exchanges on Wednesday.

Time and again, Mr McCain went after his rival – for the latter's advocacy of a fixed timetable for US withdrawal from Iraq (something Mr Romney fiercely denied), for $730m of tax increases imposed on the citizens of Massachusetts, and for job-cutting during his corporate career.

Hitherto he has come across as the feisty straight-talking underdog. Voters may now be reminded of the other McCain, hot tempered, acerbic and – vis-à-vis Mr Romney at least – almost contemptuous.

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