Pass the sickbag and fasten your seatbelts. Kerry looks like winning

America looks like a parallel universe. They do things differently there, including politics. The levels of schmaltz and saccharine in Boston last week would simply not be tolerated over here. For all the complaints about the Americanisation of our culture and politics, we are still a long way from modern US party conventions. We are a long way from hearing speeches from the candidate's wife, his daughters, his running mate's wife and his running mate's daughter. Cate Edwards, who is not running for office, gave a speech not in praise of John Kerry but of her mother, who is also not running for office, but who lives her life "with an optimism that keeps her joined to my father at the heart".

America looks like a parallel universe. They do things differently there, including politics. The levels of schmaltz and saccharine in Boston last week would simply not be tolerated over here. For all the complaints about the Americanisation of our culture and politics, we are still a long way from modern US party conventions. We are a long way from hearing speeches from the candidate's wife, his daughters, his running mate's wife and his running mate's daughter. Cate Edwards, who is not running for office, gave a speech not in praise of John Kerry but of her mother, who is also not running for office, but who lives her life "with an optimism that keeps her joined to my father at the heart".

There was plenty more of that kind of sick-making rhetoric in Boston. As the writer Jonathan Raban once observed, the modern political speech is an industrially manufactured product. And the American taste in such things is as rich and overwhelming as in so much else.

That makes it difficult for us on this side of the Atlantic to judge the success or otherwise of the Democratic convention. The ground rules of American rhetoric are subtly different. Words do not always mean what we think they mean. When Kerry spoke about the "middle class" feeling squeezed, for example, he meant roughly what we mean by "ordinary working people" over here. And, of course, he has had to change his mind about the death penalty, which he now supports for terrorists.

Despite all that, the rules of political strategy are basically the same in Britain and the US. That is why Tony Blair learnt so much from Bill Clinton's campaign in 1992, and that is why the shape of this year's ideological contest between George Bush and John Kerry is so accessible to us, despite the biodegradable balloons.

The challenge for Kerry this year is essentially the same as it was for Clinton 12 years ago, when he ran against George Bush Snr. As in Britain, US elections are won and lost in the centre ground, and Kerry had to reach out beyond the Democratic heartland. Hence the relentless emphasis on national security, Kerry's record of active service and resolution in the war on terrorism.

At the start of last week, Dick Morris, Clinton's most cynical and most right-wing adviser, criticised the Democratic Party's line-up of speakers in Boston as too liberal. Ted Kennedy and Jimmy Carter were not his idea of cross-party appeal. In the event, however, it was former president Carter who delivered the sly line about Kerry volunteering for military service: "He showed up when assigned to duty."

Former president Clinton expanded on the theme, with a reference to his own equivocation over the draft: "During the Vietnam War, many young men - including the current president, the vice-president and me - could have gone to Vietnam but didn't. John Kerry came from a privileged background and could have avoided it, too. Instead he said, send me."

It was a cleverly scripted build-up to the candidate's own best line, his first: "I'm John Kerry and I'm reporting for duty." The rest of his acceptance speech was too long. He gabbled much of it, to fit into his prime-time television slot, and wasn't sure when to pause for applause or when to talk over it. But it wasn't a disaster.

Curiously, parts of it might have sounded to British ears rather too left-wing to appeal to undecided American voters, who are generally regarded as being somewhat to the right of Basildon Man. Kerry promised, for example, to "roll back the tax cuts for the wealthiest individuals who make over $200,000 a year, so we can invest in job creation, health care and education". What? That sounds like the kind of socialism that died in this country with John Smith 10 years ago. Strangely, however, it is what Clinton, an early prophet of the third way, promised and enacted when he was first elected - higher tax on incomes over $100,000 a year. Taxing the rich does not seem to be the vote-loser in America that Tony Blair thinks it is here.

The other alarming element of Kerry's speech to New Labour ears was his forthright condemnation of Bush for "misleading" the nation into war in Iraq. Was this not Kerry's Michael Howard moment? How could he attack the President for waging a war that he supported?

Fortunately for the Democrats, Kerry is a smarter strategist than Howard. The war issue is different in the US, because Congress voted only to "authorise" military action, leaving Kerry scope to disagree with Bush about whether the UN inspectors were given enough time.

He therefore had the chance to be surprisingly aggressive in his attack on Bush. In that, he took a risk with the centre ground, because one of the basics of the Clinton-Blair rulebook is to adopt the garments of "bipartisan reasonableness". Kerry did, in fact, pay lip service to this, appealing to the President: "Let's build unity in the American family, not angry division."

And, although he mentioned Bush by name only twice, such fake restraint added venom to his indirect attacks on his opponent. But Kerry needed to be aggressive because he needed to shake off the image of a temporising flip-flopper that the Bush campaign was beginning to make stick.

One of the reasons why Kerry is a stronger candidate than many pessimistic lefties give him credit for is that he finds it difficult to hide his contempt for George Bush. During the primaries, he spoke to a Democratic audience about how the President's image was managed. "They put him in a brown jacket and jeans and get him to move some hay or drive a truck, and all of a sudden he's the Marlboro Man. I know this guy. He was two years behind me at Yale, and I knew him, and he's still the same guy." He was dismissive of Bush's "lack of knowledge", and the fact that he "didn't begin his adult life until he was 40". When challenged by a Vogue profile-writer, he back-pedalled unconvincingly: "I like George Bush. Lemme make that clear. I like him. He's a likeable fellow. He really is. Obviously. He has a great art." A "great art" indeed. But now it's time to show a bit of edge.

With the election poised 50-50 in the polls, the main potential of the Democratic convention was never on the upside, but on the down. By maintaining what the Republicans call "message discipline" on national security, the Democratic Party got through the week unscathed. Some of the jokes were even funny (such as Al Gore's opening line: "You win some, you lose some. And then there's that little-known third category.")

By not messing up, Kerry is still competitive. I think he is going to win, for the reasons rehearsed here before. He needs only one of the big states that Gore failed to win last time. He is a better candidate than Gore, even if not by much. George Bush is no longer a "compassionate conservative" but a divisive ideologue. And Democrats are motivated to turn out as never before. Let battle commence.