The more violent the protests in New York, the happier the Republicans will be

Democrats know Kerry needs the votes of those who hate Bush, but they are also aware too much hatred can put off voters

An island off the coast of America, Manhattan is the capital of a country which does not exist. A lot of the world's richest people have homes here, as does an even higher proportion of the globe's most exotic inhabitants. There were more androgynous creatures on display yesterday in Fifth Avenue than the average Thai brothel. But Manhattanites were inspiring themselves to be even more outrageous than usual. The Republican Party has come to town and the locals want to make it feel un-at-home.

An island off the coast of America, Manhattan is the capital of a country which does not exist. A lot of the world's richest people have homes here, as does an even higher proportion of the globe's most exotic inhabitants. There were more androgynous creatures on display yesterday in Fifth Avenue than the average Thai brothel. But Manhattanites were inspiring themselves to be even more outrageous than usual. The Republican Party has come to town and the locals want to make it feel un-at-home.

The Republicans' symbol is the elephant, and in one of the New York zoos, there are four of them. Judging by Manhattan street-life, if the elephants joined the Republican party, its numbers would just about double.

So it might seem odd that the Republicans decided to come here. But there were good reasons. In the first place, Manhattan is not New York City, let alone the state. The city's other four boroughs are full of work-a-day people leading normal lives, and many of them are potential Republican voters. Upstate, there are plenty of conservatives. Ronald Reagan carried the state twice; it is only in recent years that New York has seemed to drift out of the Republicans' reach.

In the immediate aftermath of 11 September, it seemed that 2004 might be a good year to put that right. Back then, there was no reason to suppose that security issues would be so divisive. George Bush showing solidarity with the violated city: what an ideal way to project presidentiality and use the power of incumbency to sweep back to office, perhaps even carrying New York state.

That now seems a long time ago. The Republicans are no longer thinking in terms of capturing New York, and some of them regret that they are not in Detroit or Philadelphia, where their presence might assist the campaigning effort in battleground states.

Yet the Republicans might derive an advantage from being in New York. However involuntarily, leftist Manhattanites might be of use to George Bush. The very intensity of their hatred could prove useful.

On Saturday, tens of thousands of pro-abortionists marched across Brooklyn Bridge, all proclaiming their loathing for Mr Bush. At one moment, I thought that they had been infiltrated by pro-lifers. A couple of elderly ladies were sharing a complicated banner which said that though they were now too old to enjoy reproductive rights, they wanted to pass them on to younger women. I was quickly corrected. By "reproductive rights'', the ladies meant the right to an abortion.

Such Orwellian use of language will not play well on the American mainland. Apropos abortion, I see no practical alternative to the right to choose, within reasonable time limits. I agree with the American commentator, Ben Wattenberg, who said that: "Abortion is murder and I am in favour of it.''

But how could anyone take pleasure in the thought? Yet those hard-faced, steel-rimmed Stalin's grannies on Brooklyn Bridge, wizened into misanthropy, gave the impression that an abortion should be a woman's greatest joy. There seemed no point in reminding them that they too had been foetuses once. There was equally little point in telling them another self-evident truth: that the more their pictures appeared on television, the more it would turn Middle Americans in favour of Bush.

On Sunday morning, before the big demonstrations got under way, the thoroughfares were full of stragglers who still looked a couple of coffees short of a full-lunged protest. Sometimes, groups would meet and merge. In London, scores of Japanese tourists will obediently follow the guide with the flag. In Manhattan yesterday, the sheepdog was the leftie with a placard.

The demonstrators were angry because they had been denied access to Central Park in case they damaged the grass. (How? Smoke it?) High words were hurled at policemen who remained obstinately polite and smiling. It seemed unlikely that there would be trouble, but Republicans can hope, and Democrats fear.

The Democrats know that John Kerry needs the votes of those who hate George Bush. They are also aware that too much hatred can put off a lot of moderate voters. A few blocks from the convention centre, the Democrats have established an HQ for spin and rebuttal. It is staffed by eager youngsters who could pass for Mormon missionaries. Forget placards; they give the impression of regarding facial hair with horror. They will be trying to persuade the public that their party is clean-shaven and patriotic, in no way to be confused with the raucous hairies on the streets. Their nightmare is that the protesters are associated with the Democratic Party.

That is the Republican dream. The party hierarchy views the demonstrators rather as the dons of Scone College viewed the drunken members of the Bollinger Club at the beginning of Decline and Fall. If the fines for mayhem reached a certain level, High Table would be served the College's finest port. If the protests turn violent, the Republicans will be served a boost in the polls.

In 1968, something similar happened during the Democratic Convention in Chicago. Anti-Vietnam War groups rampaged, Mayor Daley's police laid about them with truncheons and teargas, Richard Nixon swept in the votes. But there is not going to be a repetition in New York. The police seem to have spent the summer in charm school. Yet the Democrats have reason to fear that even non-violent protests could still persuade uncommitted voters that the people who hate George Bush have escaped from a freak show.

Nor will the demonstrators prevent the President from projecting exalted themes. The Republican strategists know that they have a problem with a false syllogism which is still hard to refute. It runs as follows: there was no terrorist threat until Mr Bush came along. So if we get rid of him, we also get rid of terrorism.

This week, Mr Bush will be trying to persuade his fellow Americans that they can no longer hope to enjoy security by cowering behind their own borders and that he was right to project power in order to pre-empt threats. When operating with a prepared text, the President is one of the finest speakers of our time. As he knows this is just about the most important speech he will ever make, he is unlikely to fail. Even without the rabble babble in the streets, the Republicans should receive a boost from this week's festivities.

Not that this will be conclusive. The next two months will see the most expensive, intensive, embittered and closely-fought election campaign in history. It will also be the tensest. One mistake by either candidate could seal the outcome, and they both know it.

Over the past few days, I have had a sense that there has been a slight swing to Mr Bush, but nothing that decisively separates neck from neck. There are weeks of hard pounding to go, all over the streets in the key states. In the meantime, we can enjoy the street comedy. If the Republicans knew their Lenin, they would recognise the presence of useful idiots.