The summit in Washington this weekend would have been a gathering of the world’s most powerful leaders, except that the man with the most potential to influence proceedings is absent from the stage.

Barack Obama has declined invitations to attend the G20, preferring to remain in Chicago, where he is putting together an administration that will take over on January 20.

He has deputed two surrogates to represent him in Washington this weekend: Madeleine Albright, the former Secretary of State, and Jim Leach, a Republican who endorsed him during the presidential election. Neither is a member of his economic advisory team, leaving them as observers, even messengers, rather than summit participants.

President Bush is struggling to quieten a clamour from European governments for tighter regulation of world finance, as well as resist Congressional efforts to intervene in the US economy through a fresh stimulus package and a $50 billion bailout of a faltering car-making industry.

Whatever the leaders — whose countries are responsible for 85 per cent of the world’s economic activity — agree this weekend, they will essentially be operating in a vacuum trying to second-guess the incoming administration. A new summit is already being planned for spring next year.

In the week before the presidential election Gordon Brown was confident that the winner would join Mr Bush in Washington this weekend. Soon after his victory, however, Mr Obama made plain that America can only have “one president at a time”.

As a senior figure in the British Government put it: “There are some tough decisions to be taken. I guess the calculation has been: ‘There’s nothing in this for us, we’ll leave it to the guy that’s going.’” According to his diplomats in Washington, Mr Brown believes that he is in broad agreement with Mr Obama on the need for and shape of international economic intervention. “The timing is difficult in terms of the transition,” said one, “but I’m sure there will be an early meeting between the Prime Minister and the new president.”

For all Mr Brown’s claims Mr Obama was careful to meet with David Cameron on his European tour in the summer, a coup that still delights the Tory leader’s team.

A Downing street aide insisted that none of that really matters. “Cameron can talk about Obama having won a ‘change election’ but the key issue was the economy. That is where Gordon has a coherent plan, where he is making the weather while the Tories — like the Republicans — remain stuck on the wrong page of history.” In the immediate aftermath of the US election, some around Mr Brown claimed that he could act in an advisory role in the manner of Harold Macmillan to John F Kennedy. This is now seen as patronising but there is still a belief that Mr Brown’s reserved character can complement Mr Obama’s style.

The summit promises to be as sober as the economic outlook with none of the entertainment and shopping trips that mark such events in more prosperous times. For instance, Carla Bruni — President Sarkozy’s wife and a reliable wethervane of glamour — is remaining in Paris. This prompted one diplomat yesterday to suggest she might have come if there had been a chance of meeting Mr Obama.

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