Mr Bush delivered his tribute from the gardens of the White House as Mr Obama hunkered down at home in Chicago to choose the men and women that will accompany him to Washington in January.

After a landslide victory that saw him chosen as America's first black president, Mr Obama knows that there is no time to lose if he wants to build an administration to extricate the US military from Iraq and deliver the change he promised to voters.

As he told more than 100,000 supporters packed into Chicago's Grant Park for his victory rally last night: "We know the challenges that tomorrow will bring are the greatest of our lifetime: two wars, a planet in peril, the worst financial crisis in a century."

The first pick on his team sheet – to be officially confirmed later today – is Rahm Emanuel, the combative but highly effective Chicago congressman who advised Bill Clinton in the 1990s. Mr Emanuel – known as 'Rahmbo' – has agreed to return to the White House as chief of staff.

Other posts likely to be filled within days include Treasury Secretary, Secretary of State and Defence Secretary - even though Mr Obama will not be sworn in as the 44th President of the United States until January. More...