Now we know what a John Kerry presidency would look like - and it is not reassuring

There are candidates who talk the talk and there are candidates who walk the walk. This one flips the flop

It was a perfectly crafted speech; one of the best of its kind that has ever been delivered. John Kerry set out to appeal to everyone and to offend no one. There were passages in the speech to reassure those who fear that a Kerry presidency would be soft on terrorism, but there was also comfort for those who hate the Iraq war.

As he had intended, the senator ticked every box, except one. There was nothing in the speech for those who want to know who Mr Kerry is or what he believes and there was no answer to the basic question: what form would a Kerry presidency take? There was a good reason why those questions remain unanswered. How could they have been? John Kerry himself does not know the answer.

He knows that he is the candidate of a party that hates its rival. If George Bush is re-elected, at least half the Democratic Party will have apoplexy. Mr Kerry is therefore aware that most Democrats are in no mood to cross-examine him on his views. They have only one demand: that he win. How? Anyhow.

Yet it may not work to his advantage that hardly any of his fellow Democrats are pressing him to define himself. That only encourages a natural tendency towards vagueness and equivocation. There are candidates who talk the talk and there are candidates who walk the walk. This one flips the flop. It is hard to believe that a lot of voters will not notice. The Republicans will be drawing it to their attention.

Moreover, the flip-flops are in long-established character. US senators serve for six-year terms. The framers of the constitution gave them that generous allowance of time in order to insulate them from the transient passions of the democratic process. It was hoped they would take broad views and display independence of mind.

Mr Kerry has done neither. Even his supporters find it impossible to claim that he has made a significant contribution to the Senate's proceedings. In one respect, he has impressed observers: his ambition. But it is ambition for himself, not his country.

The interminable length and expense of American political campaigning has one advantage. Usually, it does give the voters the chance to see candidates as they are, not as their handlers would wish them to be. It is hard to believe that Senator Kerry will be able to spend the next three months concealing the fact that he is all ego and no credo.

It is still likely to be a desperately close election that may well hinge on one issue: nervousness. Most Americans are nervous, with good reason. September 11 proved their vulnerability. Even if there is no further atrocity, the effects might take a generation to wear off. So whom will the voters blame and whom will they trust?

The Democrats' tactic is clear. They want to blame the Twin Towers on the Iraq war. This is made explicit on the party's Michael Moore wing; the Kerryites merely use body language to make the same point. They want American voters to forget about the historical sequence and to believe that the US is in danger because a lot of people dislike George Bush and because he undertook a reckless war. Get rid of him, and life will be safer. For a start, America will have allies again.

There is one problem with all that. It does not bear 10 seconds' examination, and that is especially true when it comes to allies. Is Mr Kerry seriously suggesting that he could persuade the French to protect America?

Equally, the Middle Eastern terrorists who hate America have been doing so for years; al-Qa'ida started its military campaign under Bill Clinton. There is nothing that any conceivable US president could do to appease this hatred. The only possible counter-measures will require time, perseverance, intelligence and luck. Time and perseverance, for the new Iraqi government to work, for the revival of the Palestine peace process, for reform in Saudi Arabia, for benign developments in Iraq. Intelligence, to frustrate new terrorist assaults - and luck, because even the best intelligence services need it, as will the Saudi reformers and the Allawi government.

Yet none of that will be possible unless the Americans demonstrate their resolve; their willingness, if necessary, to pay for peace not with the base currency of appeasement but with American blood. If that resolve crumbled into weakness, the entire Middle Eastern strategy and the entire counter-terrorism strategy would crumble with it.

That is why this presidential election is so important. It does not matter if Mr Kerry will occasionally sound bellicose if he thinks that the audience would approve. No one outside America is going to be fooled. The weakness candidate is challenging the resolution candidate. John Kerry is appealing to those who want America to seek safety in retreat. That is why all America's enemies - Jacques Chirac, Gerhard Shröder, the Labour parliamentary party, al-Qa'ida - are endorsing John Kerry. They know that he is the man to render American power impotent.

That cast of supporters ought to be enough to ensure the senator's defeat, but when people feel nervous they do not always think straight. Mr Bush will have to persuade enough Americans of one vital proposition: that the US cannot rely on its own borders to defend its security. Unless America is prepared to go abroad to protect itself, malice, threat and evil will mature at their leisure, several continents away from the American mainland, and choose their moment to strike and kill.

This is not the most reassuring message that any American president has put before his people. Mr Bush still has the task of persuading the soccer moms of America that he did not go to war because he enjoys combat; he did so in the interests of American security. He knows that there are occasions on which you can only arrive at safety first via the battlefield. Mr Bush now has to find a middle-American translation for that wisest of Latin tags: if you want peace, prepare for war.

That message may seem hard to sell, but it does express George Bush's deepest convictions. He is a man who does not have to wait for his speech-writers' latest draft to learn what he is supposed to believe that day. John Kerry had several months to prepare for last Thursday evening. He knew that it would be the most important speech which he would ever make, and he is not a stupid man. If he could not sound sincere in his convictions, there was only one conclusion to be drawn. He has none.

In lesser American elections there is a style of oratory that has enabled many an inadequate candidate to fool many an unsophisticated audience. It also helps those who believe that the best antidote to political speechmaking is sleep. It is called bomfog; short for the "brotherhood of man and the fellowship of God". A bomfog speech is an orotund collection of sonorous and interchangeable platitudes.

That was John Kerry on Thursday night: It was high-grade bomfog, to be sure, the best on the market, but bomfog none the less. This would be a bomfog president in a dangerous, treacherous era, the sort of world in which the "fog" bit could easily turn into a mushroom cloud.