PARIS  The choice of Barack Obama on Friday as the recipient of the 2009 Nobel Peace Prize, less than nine months into his eventful presidency, was an unexpected honor that elicited praise and puzzlement around the globe.

Normally the prize has been presented, even controversially, for accomplishment. This prize, to a 48-year-old freshman president, for “extraordinary efforts to strengthen international diplomacy and cooperation between peoples,” seemed a kind of prayer and encouragement by the Nobel committee for future endeavor and more consensual American leadership.

But the prize quickly loomed as a potential political liability  perhaps more burden than glory  for Mr. Obama. Republicans contended that he had won more for his star power and oratorical skills than for his actual achievements, and even some Democrats privately questioned whether he deserved it.

The Nobel committee’s embrace of Mr. Obama was viewed as a rejection of the unpopular tenure, in Europe especially, of his predecessor, George W. Bush.