The Nobel Peace Committee is no stranger to political controversy; its idiosyncratic decisions and non-decisions on what arguably is the world?s most famous award do tend to defy conventional wisdom.

The Nobel Committee?s choices invite acute political contestation when it rules in favour of serving presidents and prime ministers. And when the winner is the President of the world?s most powerful nation, there will be no dearth of political cynicism.

To be sure, Barack Obama is no ordinary political leader. That he has won the Nobel Peace Prize even before he completed nine months in the White House and served barely two years on the national stage prior to that, underlines the huge impact President Obama has had on political imagination in the US and in the world.

Obama?s decision to end the war in Iraq, reverse US opposition to climate change negotiations, reach out to Muslims in the Middle East, question some Israeli policies, offer negotiations to Iran, propose a re-set in the relations with Moscow, pull back from the missile defence plans in Europe, commit the US to a future elimination of nuclear weapons have clearly made a big impression on chattering classes in Europe, where the Nobel Committee resides.

Nevertheless, the committee?s announcement to give the 2009 Peace Prize to Obama is bound to generate controversy, in no place more than the US.

There is no question that the decision is a huge surprise, given reports that Obama was not of the original short list of candidates for the Nobel this year. If the International Olympics Committee snubbed the US President who flew through the night to Copenhagen and made a personal pitch in favour of his hometown Chicago which wanted to host the 2016 Olympics, the Nobel Committee seems to have more than compensated.

America?s people are bound to be proud at their President getting the Nobel. But the reaction of the deeply divided political class will underline the current polarisation in the US.

The Democrats will hail Oslo?s decision as a vindication of president?s determination to reverse the negative policies of his predecessor George W. Bush. They would also argue that if America was reviled in much of the world during the Bush years, the Nobel Prize to Obama is restoring the attractiveness of America?s soft power in the world.

The Republicans will dismiss the prize as a pathetic attempt by the Europeans to celebrate Obama?s presidency for being simply ?un-Bush? in its approach to the world.

Given the extraordinary power the United States wields over the world, it is entirely understandable that much of the world wants to express its preferences within the US political debates. In the end the outsiders have no vote in American politics and the external interventions at best feed into American political divisions.

The very reasons that Oslo cites to justify the prize ? the contribution to internal diplomacy and cooperation?are strongly questioned in the United States. What European liberals find endearing in Obama?s foreign policy angers American conservatives.

American critics of Obama?s foreign policy argue that the president has been too apologetic about America?s past conduct. Even more seriously, they insist that Obama is subordinating the US national interest in the name of a wooly-headed internationalism.

Worse,they suggest Obama my be endangering American security by underestimating its enemies and letting other major powers like Russia and China squeeze the maximum of America?s presumed weaknesses under the Obama Administration.

Beyond the partisan arguments in the US, Oslo is certainly vulnerable to one genuine criticism. That it has rewarded the international promise of President Obama rather than his performance.

At this moment many of Obama?s international initiatives are not even half-cooked. It is by no means certain that Obama will be able to deliver on any of his major promises?such as those on global warming, nuclear disarmament, and peace in the greater Middle East.

No other chief executive of any large nation is as constrained by the internal political structures as the US President. The system of constitutional checks and balances means the US Presidents have a hard task creating domestic consensus on foreign policy.

Despite the general endorsement of Obama by the American people and the rare simultaneous control of the Congress by his own party, every major international initiative of Obama faces massive political hurdles at home.

Obama may deliver on some of his promises and fail on many. It would have been prudent then for the Nobel committee to wait for an assessment of the outcomes from Obama?s policies rather than their intentions. After all, Obama is facing criticism from many of his liberal supporters for failing to keep his promises.

But the Nobel Peace Committee is nothing if it is not a political beast that loves joining the fray and picking up winners who it would like to succeed.

The writer is Henry A. Kissinger Chair in Foreign Policy and International Relations at the Library of Congress, Washington, DC