John Rentoul: The primaries show – opening here soon

The Tories are seeking pointers from the US as avidly as New Labour emulated Bill Clinton's tactics in 199

There are two schools of thought in this country about American politics. One is that it is all hugely entertaining but of no relevance to us – except in the obvious sense that the whole world has an interest in who leads its most powerful nation. The other is that it is all hugely entertaining and that the lessons learnt over there will be applied over here in a matter of minutes. Then there is also a third school of sour and embittered people who dislike anything American and who say that we ought to pay more attention to the fact that Slovenia has just taken over the presidency of the European Union. But nobody listens to them.

How could we, when the drama of New Hampshire is so compelling, so human and so accessible? How could we not be entranced by the thrill of the unexpected? How could we not enjoy the satire? Last week, the comedian Stephen Colbert pointed accusingly at the television camera: "If you keep voting the way you want rather than how we tell you that you want, then pundits are going to stop telling you how to think."

The US election is a great show, with dialogue as sharply written as anything on Friends. In a debate last weekend Scott Spradling, a TV presenter, asked Hillary Clinton why voters were "hesitating on the likeability issue, where they seem to like Barack Obama more?"

"Well, that hurts my feelings,"said Clinton with a smile. "But I'll try to go on."

Obama chimed in on a wrong note: "You're likeable enough, Hillary."

Then there was the display of on-message emotion in Cafe Espresso in Portsmouth: "We do it, each one of us, because we care about our country. But some of us are right and some of us are wrong. Some of us are ready and some of us are not."

Hillary was followed by her husband, later that day on the eve of polling, who was indignant that Obama had "never got asked one time, not once", about his apparent changes of view on the Iraq war. "Give me a break," said Bill Clinton. "This whole thing is the biggest fairy tale I've ever seen."

But we are more than mere spectators in all this. I belong to the second school of American politics enthusiasts: we are non-voting participants in the New Hampshire primaries.

This week, we will be taking part by proxy in the Republican caucuses in Michigan, and the Democratic caucuses in Nevada – although they are less interesting, because Clinton has a 20-point lead in the polls there, whereas Michigan is a three-way tie between John McCain, Mitt Romney and Mike Huckabee.

Anyone who believes the old saw (attributed, without evidence, to George Bernard Shaw) that we and the Americans are divided by a common language should observe George Osborne, the shadow chancellor.

In a speech at the London School of Economics on Friday, he attacked Gordon Brown for increasing public borrowing during the boom, leaving the country unprepared for economic turbulence. "He didn't fix the roof when the sun was shining," said Osborne in the advance text. What a phrase, I thought. What a vivid way to capture what should make us all uneasy about Brown's record – his failure to balance the books in the good times.

My second thought was: Where did he get it from? Clever though he is, it seemed unlikely that Osborne thought it up himself. (The speech he actually delivered on Friday differed from the advance notice: he inserted "as the old adage goes ..." as if to pre-empt the charge of plagiarism.) A few minutes on Google tracked it down. John F Kennedy's first State of the Union address in January 1962: "The time to repair the roof is when the sun is shining." It is curious that Osborne's "fix" sounds more American than JFK's "repair". But perhaps it did not come directly from Kennedy, because Kennedy is, after all, the Shakespeare of the English-language political phrase book.

So it proves. Who is this, only 10 years ago? "You don't fix the roof when it's raining. You fix the roof when the sun is shining. The sun is shining on America." It was Bill Clinton, at bay over his affair with an intern called Monica Lewinsky, defending his budget against Republican cuts. Just as Kennedy was asking for spending powers to protect against recession, Clinton wanted to hire more teachers to reduce class sizes.

What is interesting is that the idea changed its meaning more by crossing from left to right than it did by crossing the Atlantic. Kennedy and Clinton used it to argue for public spending; Osborne uses it to argue for a balanced budget. Which is why – brilliant though the phrase is – it doesn't quite fit.

Osborne may be half right, but he is also half wrong. The fact is that Brown has repaired the roof while the sun was shining. As the sun of economic growth shone, Brown fixed the roofs and buildings of schools and hospitals and invested in public services. The criticisms that count are that it went too far and that too little reform was sought in return.

The reason we have not had more crossover from the US primaries into our politics is because Hillary Clinton's surprise victory upset the analogies David Cameron was preparing to make. On the day of the New Hampshire vote, he said: "What's interesting about Obama is he is saying, 'We are America – we can do anything'. We want that same sense in Britain." Yes, we do, but by Wednesday morning, we did not necessarily want to attribute it to Obama any more.

The pollsters and the pundits were not the only ones embarrassed by Clinton's success. The Tories had already written their script to the American template. Cameron was Obama: optimism, uplift and "the audacity of hope". Brown was Clinton: experienced, familiar and polarising. Now Cameron might have to play John McCain, which is much less exciting, unexpected and youthful.

So it will be a different template, but it will still be heavily influenced by the United States. Cameron's team have read the political insider's in-book of the moment, Words That Work, by Frank Luntz, a Republican pollster who specialises in translating politician-speak into English.

Luntz's book is, for today's Tory modernisers, the equivalent of Speaking American, David Kusnet's handbook for Bill Clinton's 1992 campaign, which was a set text for Labour modernisers in opposition then.

The Clinton campaign was the big moment in the export to Britain of US political language, ideas and tactics. The formative event in New Labour history was the visit by Tony Blair and Gordon Brown to the victorious Democrat campaign team after the election.

Cameron and Osborne are trying to emulate them, but they don't yet know which candidate will win. When they do, we can be sure that they will try to copy the winning campaign. So sit back and enjoy. Mike Huckabee, by the way, is the one that looks like Robert Lindsay. Enjoy, but learn, and expect it over here faster than you can say JFK.