Today's rendezvous at the White House is the most crucial diplomatic meeting of Tony Blair's career, as the political futures of both himself and George Bush hang on pulling Iraq back from the brink. A change in events on the ground must start with a change of approach in the White House, but securing such a shift in direction will not be easy, and the personalities of the two participants make it more difficult.
Tony Blair is a man of immense, attractive charm, which he maintains by shrinking from disagreeable exchanges. Everyone who has worked with the Prime Minister is familiar with the universal tendency of visiting dignitaries to leave pleased with what they have heard - or what they believe they have heard. Spelling out bluntly to someone as powerful as the President of the United States that he has got it wrong is what Tony Blair must do today.
It does not help that George Bush keeps reminding us that he has got the Almighty on his side. This cramps his scope for tactical flexibility, and his statement on Iraq this week exuded the certitude of revealed religion.
Half the problem is that a year after "liberating" Iraq, President Bush will keep discussing the continuing US presence in the terms of "waging a war", "staying on the offensive" and "defeating enemies". There is no prospect of his leading a successful reconstruction of Iraq so long as he regards large parts of its population as enemies.
His delusion that progress in Iraq can be secured through military victory regardless of political cost appears fully shared by US commanders on the ground. General Ricardo Sanchez is massing troops with the stated intention that he will "kill or capture Sadr". However, Muqtada Sadr has taken refuge in the shrine at Najaf, one of the two holiest Shia sites, and storming it would be the equivalent of attacking Canterbury Cathedral.
The most important job for Tony Blair today is to convince the Bush administration that it is not engaged in a military operation to beat a discrete enemy but in a political exercise to win the hearts and minds of a whole people. It would help to recover some of the immense ground lost in Iraqi public opinion if at least one Marine was charged with an offence arising from the deaths of 350 women and children in Fallujah. Instead, the spin from Downing Street is that the Prime Minister is going to Washington for a show of solidarity and joint resolve to the strategy of handover on 30 June.
There are two obvious problems with this briefing. The first is a problem common to both Britain and the US. There is zero substance to the supposed hand-over strategy. We have not yet decided what actual powers we are going to hand over. Even more remarkably, we have no idea to whom we are going to hand them, or even how they will be picked. The joint resolve we will be demonstrating this afternoon is a determination that on 30 June we will do something, we know not what.
The second problem is specifically British. By committing ourselves in advance to showing solidarity with President Bush, we have thrown in our negotiating hand. Our support for the President should have been conditional on his agreeing to a strategy in Iraq of minimal use of violence and maximum speed to a democratic, legitimate government.
Our own long history of colonial occupation has taught our army that there is a Newtonian law of military force. The application of military force by an occupier tends to produce an equal and opposite resistance by the occupied. That is why Osama bin Laden must be regarding events in Fallujah and Najaf with glee. What he wanted to achieve by demolishing the Twin Towers was confrontation between the West and the Arab world, and that is what George Bush has delivered in Iraq.
And now he has delivered it in the Middle East too. The real significance of the exchange of letters this week is that President Bush has decided that his role in the Middle East peace process is not to hold the ring for a negotiated settlement but to get into the ring and punch alongside Ariel Sharon for an imposed solution. The starting point for all British and US efforts to promote an agreement in the Middle East has been Security Council Resolution 242, drafted by Britain and demanding Israeli withdrawal from the territories it occupied in the 1967 war. President Bush has just declared that UN resolution unrealistic.
There could not be a clearer illustration in Arab eyes of the double standards of the West than our demand for absolute support for UN resolutions on Iraq coupled with our cavalier dismissal of UN resolutions on Israel. After his capitulation to Sharon's demands, it is inconceivable that President Bush will command any support in Arab capitals for US objectives, in Iraq or in his War on Terror.
There was always a wild implausibility in President Bush posing as an honest broker. Psychologically he lives in a private world of stark choices between good and evil, which leads him to polarise the real world into those who are with him in fighting evil and those who are against him. The clear message this week is that he has decided that Sharon is with him, which carries the consequence that the Palestinians are against him.
It is only because he has looked at the new package from Sharon's standpoint that President Bush can describe it as "realistic". From the Palestinian perspective, what can possibly be realistic about his insistence that they should accommodate returning refugees in an area of territory that he has sharply reduced?
I do not know if anyone at the State Department was rung up before the White House endorsed such a one-sided settlement. I cannot believe that diplomats at the Foreign Office were complicit in the surreal statement from Downing Street that President Bush's new position could inject new life into the road-map. George Bush has just unplugged the road-map from its life-support apparatus, characteristically with no consultation with the UN, his supposed partner in the process.
And how dare Downing Street demand that the Palestinian Authority should "show political will" in submitting to this fresh humiliation when it has been unable to persuade President Bush to show the political will to pressurise Sharon to deliver his side of the bargain?
Famously, Tony Blair promised Labour MPs that if they supported the invasion of Iraq he would deliver George Bush's support for the road-map. George Bush could not have delivered a worse snub to Tony Blair on the eve of their meeting than to abandon that road-map. The Prime Minister may not be able to rescue the peace process, but at least he should feel freed from demonstrating solidarity with the policies in Iraq of a president who has so comprehensively failed to show solidarity with our joint policy on the Middle East.