The killing of Osama bin Laden sharply boosted President Barack Obama's image, improving Americans' views of his leadership and his efforts to fight terrorism, a Reuters/Ipsos poll released onltiesday found.

About four in 10 Americans say their opinion of Obama improved after he ordered Monday's successful US military operation in Pakistan to kill bin Laden, the mastermind of the September 11, 2001, attacks in New York andWashington.

But the boost to Obama's popularity from bin Laden's death could be short-lived as voters focus again on the economy and lingering unemployment — top concerns heading into 2012 election campaign.

"There is no evidence the boost in his approval rating will last until the election, but an event like this could position Obama as more of a military leader and give him more authority," Ipsos pollster Julia Clarksaid.

That could put a long-term dent in Republican efforts to paint Obama as weak and indecisive on national security, particularly after criticism he was slow in reacting to the "Arab Spring" protests in the Middle East and North Africa.

"The way we perceive Obama could change, and that will help him in the long run," Clarksaid.

Obama's approval rating has slumped into the mid-40s in recent weeks as voters have grown increasingly pessimistic about the future and upset at rising gasoline prices.

Obama's biggest task during the campaign is likely to be to convince Americans he is turning the corner toward an economic recovery, and to re-engage the young and first-time voters who helped propel him to victory in2008.