Do not underestimate the power of lame ducks. American presidents, in their last year of office, have frequently turned to the intractable issue of the Middle East, occasionally with small, though sadly not lasting, success. There is again a genuine window of opportunity in the region, constricted though it might be, largely because of the efforts and involvement of two men: George Bush and Tony Blair.

Both are in the twilight of political power, but both can still focus the very real determination of the outside world to end this long and debilitating conflict. President Bush is free of the constraints of a vociferous domestic pro-Israel lobby; Mr Blair can equally ignore the pro- Palestinian bias of many British and European politicians. Together, they can bring balance and determination to the hobbled peace proposals that have moved little since Annapolis.

The paralysis has largely been caused by a lack of political power in both Jerusalem and Ramallah. Ehud Olmert, a former hawk who voted against the Oslo peace accords, has committed himself to a Palestinian state and most of the “road map” to peace, but since the Lebanon war has been constricted by almost unprecedentedly low approval ratings. Mahmoud Abbas, the Palestinian President, has still not recovered from his Government's humiliating rout in Gaza by Hamas, and has been unable to show to loyalists on the West Bank any reward for his readiness to talk to the Israelis.

Both, however, should seize the new opportunity to break the stalemate. The window of Western political will is going to last only so long. By the beginning of 2009, there will be a new president in the White House and Mr Blair is likely to be looking for a political post in Europe. The former Prime Minister's other political ambitions will continue to hover in the background, but for the moment he is taking his role as special envoy seriously. He is learning at first hand the first frustrating complexities of the Middle East. But he told The Times that what matters is to change the facts on the ground: for unless Israelis receive assurance on their security concerns and the occupation is lightened for the Palestinians, any political deal becomes hard to cut. That means, specifically, immediate moves by the Israelis to halt settlement activity and remove illegal outposts as well as cutting back the road blocks on the West Bank. Unless the Palestinian economy could be revived, there would be no incentive for them to make any concessions.

The Palestinians must do more on security. Mr Blair repeatedly condemned the rocket attacks launched from Gaza. But he said that the present policy of isolating Gaza was not working, as the people there felt they were being punished for the actions of extremists. The aim should be to help the people and isolate the extremists, not vice versa.

Mr Blair has raised a huge sum - $7.7 billion - to get the Palestinian economy moving. What he and Mr Bush must do is to instil a sense of urgency and confidence that this money can and will make a difference. Otherwise it will be squandered. Neither side can afford to wait. Mr Olmert, whose ratings have begun to recover, need to take the bold steps for peace that a majority of Israelis favour if he is to recover his political standing. Mr Abbas needs to show results on the West Bank if the angry and frustrated people of Gaza are to support an alternative to the intransigence of Hamas. Delay in Jerusalem will only increase pressure on the fractious coalition and early elections sweeping Binyamin Netanyahu and the Right back into power would halt any further moves to peace.

A new American president is unlikely to make the Middle East a priority in the way that Mr Bush now has this partial freedom to do. Nor can the Palestinians continue to count on regional support from fellow Arab states. There should be no illusion about the difficulties, especially of dealing with Hamas, which has articulated no policy beyond an uncompromising rejection of any modus vivendi with Israel. But the makings of an overall deal are in place. They must be seized this year.