Yes, Prime Minister, but can you hang on?

The late Peter Jenkins was shortly to set off for Washington to be The Guardian's correspondent there, and he was chatting to a few of us about what he could expect.

"The difficulty I feel," he said, "is how close I should get to the President."

The incumbent in question was then Richard Nixon. One of our company had recently returned from a lengthy stint in Washington himself.

"Don't be so silly, Peter," he said. "He won't even know you're there."

"Oh I think he will. The Guardian's quite an important paper."

"Well, it may be important over here, but over there they've never heard of it. You'll be ranked just above a Dutch journalist."

So it turned out, and Jenkins never forgave Nixon for his neglect. This small story has kept coming back to me in the last few months. Prime Ministers are, I know, different from Washington correspondents. But they are not entirely different. They too have their vanities and their delusions, as the Labour Party has as well.

One of the party's favourite tales is about how C R Attlee as Prime Minister flew to Washington to stop Harry Truman from using the atomic bomb in the Korean War. Roy Jenkins deals with this story in his life of Truman: "The myth that Attlee's visit stopped Truman starting nuclear warfare in Korea can be quickly disposed of. Truman had no intention of doing any such thing, but he had mainly himself to blame for the fact that such a fear had become widespread."

Harold Wilson used to claim influence too. Alas, his various "peace initiatives" in Vietnam have not assumed the same position in party mythology as Attlee's flight to Washington. Poor Wilson was vilified at the time for lending British support to the United States. Support, he used to say, was the price he had to pay for influence. But it did not extend to sending a single squaddie to Vietnam, even though Lyndon Johnson asked several times for a "token presence".

Mr Tony Blair, by contrast, believes that something considerably more than a token presence is required to provide any influence with the present US Administration. And, to be fair, he can make some claim to success. He has pushed the Administration into taking the United Nations pathway to Iraq, though possibly it would have done so anyway under the influence of such figures as Mr Colin Powell.

The dispute in the Labour Party is about the point at which this path peters out and reverts to scrubland. Mr Blair believes that the US and the UK can take their machetes – or weapons billions of times more powerful than machetes – and hack away if the cause is just. He does not intend to be put off by vetoes exercised by Russia, China or anybody else or by tiresome rules of procedure as adumbrated by international lawyers and other tedious persons of that kind.

At the moment he is confident that these procedural requirements – notably the second UN resolution, which may or not be legally necessary – will duly be met. If they are, he probably has the support of a majority of the parliamentary party and most of the Cabinet. If they are not met and we still go to war, anything can happen, including the removal of Mr Blair. Of course there are many, such as Mr George Galloway and Mr Tam Dalyell, who are, entirely reasonably, opposed to war against Iraq in any circumstances whatever, with or without the authority of the UN. But the bulk of the party will rebel if military action is taken without that authority.

Mr Blair's position appears stronger than it is largely because of an outbreak of sincerity for a few minutes at the end of Prime Minister's Questions. It was in reply to a wholly legitimate question from the nationalist Mr Elfyn Llwyd. True, it was in somewhat pious Welsh terms about which, naturally, our racist sketchwriters had a high or, rather, low old time. He was asking about the morality of a war against Iraq. Mr Blair replied that it was the very model of morality. Iraq would shortly be exporting weapons of mass terror to evil-doers all over the globe – a proposition for which there is not the slightest evidence.

There was then a somewhat confused message about the bombing of Afghanistan. What it seemed to amount to was that, if someone had told people that they could prevent the 11 September outrage by bombing that country first, they would not have believed it. Well, no. It is not at all clear that destroying the Taliban first would have prevented the operations of al-Qa'ida which had originated in Saudi Arabia. It was complete raving from start to finish. But the easily impressed inhabitants of the Press Gallery lapped it up. So did the entire Tory opposition and even a few Members on Mr Blair's own side.

If I were a regular attender at the Prime Minister's press conferences (which thank the Lord I'm not, sir), the type of question I would ask would be: How confident are you, Mr Blair, that you will still be Prime Minister at the end of the year? In The Independent last week Mr Alan Simpson, in an article opposing any war with Iraq, wrote: "The Iraqi-style democracy of New Labour means that a leadership challenge is not constitutionally possible."

Not so. When there is a Labour Prime Minister, the MPs cannot call an election. But the party conference can. What is required is a simple majority on a card vote that an election should be held. The contest is then thrown back to the parliamentary party.

If there is a vacancy, the candidates must receive the support of 12.5 per cent (or 52) of Labour MPs. If there is no vacancy but, rather, a challenge, the figure rises to 20 per cent (or 82). It is not wholly clear whether the displacement of a Labour Prime Minister by the conference counts as the creation of a vacancy or not. Nor is it clear from the rules whether Mr Blair, were he to suffer such an ungrateful fate, would have to retire from the contest or be eligible none the less to stand in the ensuing election, if he obtained the requisite level of support from his MPs.

At the third stage the electoral college comes into operation, with a third share each for MPs, individual members and trade unions. It is one of the great confidence tricks of modern politics that New Labour has somehow been converted to the principle of one member, one vote.

Mr John Edmonds, Mr Bill Morris and other paladins of the block vote (which now controls only 50 per cent of the conference) are not going to use their power to call for an election unless they have some idea of their candidate. Last week there was a brief glimpse of Mr Gordon Brown, as rare as a sighting of the Great Ayrshire Grouse. He said that "a dictator who persistently defies the international community" must be "punished". But with Mr Brown you never know, any more than you do with Mr Robin Cook.