US President Barack Obama's considerable charisma seems to have lost some of its lustre as he juggles formidable domestic and international challenges.

That point was hammered home with a stinging rebuff from the International Olympics Committee on Friday.

Instead of ending the week basking in the success of his diplomatic efforts to bring Iran to book, Obama suffered his first embarrassment on the international stage.

His home town of Chicago lost its bid for the 2016 games to Rio de Janeiro despite a personal appeal by the once unbeatable team of the American leader and his First Lady.

Using elements that have become familiar themes in his speeches, Obama wove in the story of his historic electoral triumph while making the case for Chicago.

"Nearly one year ago, on a clear November night, people from every corner of the world gathered in the city of Chicago or in front of their televisions to watch the results of the US presidential election," said Obama.

"Their interest wasn't about me as an individual. Rather, it was rooted in the belief that America's experiment in democracy still speaks to a set of universal aspirations and ideals."

He also held out another crowd-pleaser - a chance to be part of America's great return to multilateral diplomacy.

"We stand at a moment in history when the fate of each nation is inextricably linked to the fate of all nations - a time of common challenges that require common effort," he told the Olympics committee.

"And I ran for president because I believed deeply that at this defining moment, the US has a responsibility to help in that effort, to forge new partnerships with the nations and the peoples of the world."

No matter. Chicago was the first city to be voted off the list of contenders.

The White House was hard-pressed to explain why the 20-hour trip to Copenhagen was not a setback for the President. After all, he had invested energy in the failed bid at a time when urgent matters such as health-care reforms beckoned.

"All he lost was some sleep," said press secretary Robert Gibbs.

To no one's surprise, the Republican Party seized on the issue, criticising Obama for chasing the "wrong priorities".

It did not help that he returned home on a day when the labour department's latest figures showed that the United States unemployment rate hit 9.8 per cent last month, the highest since June 1983.

Cashing in on Obama's charisma has been an integral part of his administration. When his first big move as President - the economic stimulus package - hit resistance, Obama hit the town halls.

When his signature domestic initiative - the overhaul of the health-care system - faltered, he responded with a nationally televised speech to Congress and more town hall meetings.

In his first nine months in office, Obama has given more prime-time news conferences and joint addresses to Congress than any of his predecessors in the same period.

Despite all that talk, however, most of the President's agenda items are still works in progress.

Health-care reforms will continue to be hotly debated in Congress over the next six weeks, while a new poll reveals that most Americans think he has not done a good job of explaining his plan adequately.

His biggest foreign policy priority - Afghanistan - demands a decision soon on whether or not to add more troops to the ground.

Before the year ends, Obama will make another trip to Copenhagen, to participate in negotiating a son-of-Kyoto Protocol to replace the old treaty.

Also on Obama's plate are: winding up the war in Iraq, carrying out promised financial regulation and bank reforms, and the closure of Guantanamo Bay.

While Obama has long been a target of the right-leaning media, now even moderate and liberal commentators are finding fault with him.

"It's time to act like a president," a Washington Post column admonished him last week, knocking the President for choosing television appearances over policymaking behind closed doors.

Certainly, the Chicago setback will soon be forgotten but it is clear that unless Obama shows solid progress in meeting his goals, he will end up with substantially diminished clout.