There may seem to be an element of gratuitous cruelty in describing today's Washington meetings between Tony Blair and George Bush as the lame-duck summit. Yet there is surely a large element of truth as well, and it limits the usefulness of this encounter.
Both the British Prime Minister and the US President are contemplating the end of their respective periods in power: Mr Blair because he has stated his intention of not fighting another election; Mr Bush because he will leave the White House in January 2009. His room for manoeuvre may shrink even before then, if his Republican Party has its wings clipped in November's mid-term congressional elections.
Both are diminished figures domestically: their approval ratings have sunk to rock bottom. Mr Blair may enjoy celebrity status in the United States, but at home his government is mired in the serial scandals that mark the tawdry end of an era. Mr Bush, not before time, is starting to face searching questions from Congress over Iraq. Popular resistance to the war and its human cost has grown inexorably since Mr Bush secured his second term. Like Mr Blair, he looks a far wearier, and perhaps wiser, man than he did when first elected.
Not for the first time, Mr Blair's chief role in Washington will be as envoy. He arrives hot-foot from Baghdad, where he met key members of the new Iraqi government. He may be able to give Mr Bush another perspective on developments in Iraq. Whether it will be any more optimistic than the one the President is receiving from his own people on the ground must be questionable. Spoken or unspoken, the most urgent subject of the day will be the desirability of troop withdrawals. This was clearly on Mr Blair's mind when he flew to Baghdad; it will surely be central to the discussions in Washington.
The rest of the agenda almost writes itself: the deteriorating security situation in Afghanistan; the mayhem in Gaza, the lack of progress in the Middle East. Thereafter might come efforts to agree a negotiating position on energy security before the G8 summit in Russia, and finally the stand-off over Iran's nuclear ambitions. But, in an interview with the Arabic television station, al-Jazeera, on the eve of his departure - an interesting choice of station and time - Mr Blair stated directly that Britain did not want a conflict with Iran as "we have enough on our plate doing other things".
Whether Mr Blair genuinely fears that the British military risks becoming overstretched, or simply wished to align himself publicly with the European preference for diplomacy before setting off for the US, his message was unambiguous. He was deliberately setting a distance between Britain and Washington, which did not exist four years ago.
As the influence of these two leaders wanes, it is hard not to ask what the Blair-Bush relationship might have achieved without the historic mistake of Iraq. At the outset, there was promise of joint diplomacy in the Middle East. After the attacks of September 11, there was the prospect of joint leadership of a US-European alliance against terrorism. There was hope of a new bridge between the US and Europe.
The two leaders meet relatively rarely now, except under the cover of multinational gatherings. The last Washington bilateral was 18 months ago. When Mr Bush comes to Europe now, he tends to avoid stopovers in London. Personally, he might be welcome in Downing Street, but politically he has become a liability to the Prime Minister. In the end, the war that Mr Blair entered to cement an alliance has achieved the opposite. Not only has it pushed the US and Europe apart, it has blighted the so-called special relationship for as long as its authors remain in power.