British politics, you see, has become an import business. Perhaps it has been going on longer, but I’ll tell you when I first became aware of it. It was in the early 1990s, when sitting in the offices of Bill Clinton’s favourite Washington think-tank. “By the way,” the director commented casually. “I saw a couple of your fellow Brits the other day. One of them was called Brown and I forget the other guy’s name.”

Tony Blair, it turns out, was paying more attention. Almost every political move he made in the next decade and a half was a straight steal from the Clinton campaign.

New Labour (an obvious copy of Clinton’s New Democrats); triangulation (deliberately distinguishing yourself as much from your own party as from the opposition, a strategy developed by Clinton’s guru Dick Morris); the war room (a facsimile of Clinton’s integrated political campaign operation); rapid rebuttal (Clinton’s campaign manager James Carville advised hitting back hard against the smallest negative story and trying to “win” every news cycle); constant carefully tested bite-sized initiatives (another Dick Morris tack). All of it followed Clinton. John Prescott even chipped in by having sex in his office with a member of staff.

The Conservatives, meanwhile, have brought us John Major’s “Opportunity for All” (inspired by Republican Jack Kemp); William Hague’s Common Sense Revolution (the campaign slogan of Canadian Tory Mike Harris); the heavy Australian involvement in Michael Howard’s 2005 campaign; and, of course, David Cameron’s use of the label Compassionate Conservative (© George W. Bush).

So what is the next big thing? Where will the new slogans and tactics come from? I think the next big thing will be the presidential campaign of John McCain.

The Republican senator from Arizona is 69 years old, he has unsuccessfully sought the presidency before, he has a fractious relationship with his own party and, even though he is the current front-runner, he may well fail to secure the Republican nomination. But even a short-lived McCain run still has the capacity to enliven politics in this country.

Central to McCain’s appeal is something no British front bencher can replicate — he is a war hero. As a young pilot he was shot down in the Vietnam war and, nursing terrible injuries, spent five harrowing years in a prisoner-of-war camp. Because his father was an admiral, the Vietnamese wanted to release him early, hoping by this favouritism to undermine US morale. McCain refused. First in, first out was the rule, he said. He was not about to breach the military code of honour.

But McCain has used his story to articulate a broader theme. Life, he argues, is about more than getting what you can. It is also about sacrifice. His alternative to the Clinton-Blair era of consumer politics, the politics of small initiatives, targets, and promises, is to ask voters to pitch in and make a better society rather than just offering them one. He plans to use the presidency as a bully pulpit, as did his great hero, Theodore Roosevelt. His allies in the media have dubbed his message National Greatness Conservatism.

If it fails, McCain’s message is merely airy waffle, replacing broken promises with fuzzy nothing. But if it succeeds, it can bring a more cohesive nation, a sense of national direction and duty, a restored world reputation.

There are already some similarities between McCain’s policies and those of David Cameron. Both, for instance, have promoted the idea of a national service corps, both have a strong interest in the ethical behaviour of businesses and both favour a muscular foreign policy. While they both support tax cuts and limited government, they talk about them less than the standard conservative politician. Like Teddy Roosevelt and his Bull Moose party (the nickname for Teddy’s Progressives), they are interested in what government has to do as well as what it shouldn’t do. And in this, neither of them is afraid to take on business. Cameron has not yet used the theme of sacrifice, but it is not hard to see him doing so. Both he and the McCainiacs talk of “one nation”.

The match, then, is potentially a good one. The two are already walking in lock-step. Early meetings between McCain and Cameron’s team were extremely successful. But there remains one way in which the McCain influence might change David Cameron and his Conservative campaign rather noticeably.

John McCain’s campaign bus during his last presidential run was called the Straight Talk Express, and the political action committee promoting his next run is called John McCain’s Straight Talk America. To some extent his advisers were trying to make a virtue out of a vice. McCain likes to talk, and he’s happy to talk to reporters about anything and everything. He’s also capable of petulant outbursts and undiplomatic public shows of irritation. Rebranding their garrulous candidate a “straight talker” is probably the best thing they could do in the circumstances.

Yet there is more to it than that. The eminent political journalist Joe Klein (author of Primary Colours) has just produced Politics Lost, a two-footed attack on the synthetic soundbite politics urged on US candidates by their political consultants. He wants to see more of what he calls Turnip Day moments, so-called because of Harry Truman’s spontaneous, unpolished speech in which he talked of the day the inhabitants of his home state sowed turnips.

Though a Democrat, Klein believes McCain represents the best hope for producing such Turnip Day moments. The McCain ascendancy could see spontaneity, authenticity, independence of spirit and the unspun candidate rise with it.

And if it does, just sit back and watch it change British politics.

daniel.finkelstein@thetimes.co.uk

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