(CNN) -- President Obama said Friday that he was "surprised and deeply humbled" by the decision of the Norwegian Nobel Committee to award him the 2009 Nobel Peace Prize.
President Obama, speaking Friday, said the award was "an affirmation of American leadership."
The committee said it honored Obama for his "extraordinary efforts to strengthen international diplomacy and cooperation between peoples."
Obama said he viewed the decision less as a recognition of his own accomplishments and more as "a call to action."
The decision appeared to catch most observers by surprise. Nominations for the prize had to be postmarked by February 1, only 12 days after Obama took office. The committee sent out its solicitation for nominations last September, two months before Obama was elected president.
Obama had not been mentioned as among front-runners for the prize, and the roomful of reporters gasped when Thorbjorn Jagland, chairman of the Nobel committee, announced that the president was the winner.
The Nobel committee recognized Obama's efforts at dialogue to solve complex global problems, including working toward a world free of nuclear weapons. Watch CNN's Christiane Amanpour's analysis »
"Only very rarely has a person to the same extent as Obama captured the world's attention and given its people hope for a better future," the committee said.
Jagland said the decision was "unanimous" and came with ease. Watch the 2009 Nobel Peace Prize announcement »
He rejected the notion that Obama had been recognized prematurely for his efforts and said the committee wanted to promote the president just it had Mikhail Gorbachev in 1990 for his efforts to open up the Soviet Union. Ed Rollins: Obama now must earn it
"His diplomacy is founded in the concept that those who are to lead the world must do so on the basis of values and attitudes that are shared by the majority of the world's population," the committee said of Obama. Listen to Jagland explain why Obama was this year's choice »
Obama said he did not feel he deserved "to be in the company" of past Peace Prize winners, but would accept the prize while pushing for a broad range of international objectives, including nuclear nonproliferation, a reversal of the global economic downturn and a resolution of the Arab-Israeli conflict.
He also acknowledged the ongoing U.S. conflicts in Iraq and Afghanistan, noting that he is the "commander in chief of a country that is responsible for ending a war and working in another theater to confront a ruthless adversary that directly threatens the American people" and U.S. allies.
"This award is not simply about my administration," he said. It "must be shared" with everyone who strives for "justice and dignity." Watch Obama react to receiving the prize »
It was just before 6 a.m. that the president learned he had won the award, said Robert Gibbs, the White House press secretary. The announcement by the committee caught the White House off guard. One senior administration official said that "we were quite surprised."
Some analysts have speculated that the prize could give Obama additional clout as he forms a new strategy for the war in Afghanistan and attempts to engage Iran and North Korea. Another senior administration official told CNN he hopes the White House can "use it for the positive."
The domestic political consequences are unclear. Obama's supporters hope the prestige associated with the prize will strengthen the president's hand in the health care reform debate. A top Republican from George W. Bush's administration, however, argued that "this will backfire on them for a while" and asserted it was "a gift to the right." Zakaria: Nobel honors Obama's 'bold gambit'
Obama, the first African-American to win the White House, is the fourth U.S. president to win the prestigious prize and the third sitting president to do so.
Former Finnish President Martti Ahtisaari, last year's laureate, said it was clear the Nobel committee wanted to encourage Obama on the issues he has been discussing on the world stage.
"I see this as an important encouragement," Ahtisaari said.
The committee wanted to be "far more daring" than in recent times and make an impact on global politics, said Kristian Berg Harpviken, director of the International Peace Research Institute. Praise, skepticism greet Nobel announcement
While most Nobel prizes are awarded by committees based in Sweden, the Peace Prize is determined by a five-member panel appointed by the Norwegian parliament.
Wangari Muta Maathai, the Kenyan environmentalist who won the 2004 Peace Prize, said the win for Obama, whose father was Kenyan, will help Africa move forward.
"I think it is extraordinary," she said. "It will be even greater inspiration for the world. He has shown how we can probably come together, work together in a cooperative way."
Mohamed ElBaradei, who won the 2005 Peace Prize for his efforts to prevent nuclear energy being used for military means, said Obama deserved to win for his efforts to bring Iran to the table for direct nuclear talks with the United States.
"I could not think of anybody who is more deserving," said ElBaradei, the chief of the International Atomic Energy Agency. Listen to ElBaradei react to the announcement »
The award comes at a crucial time for Obama, who has multiple administration officials dispatched on global peace missions.
Obama's envoy to the Middle East, George Mitchell, has returned to the region to advocate for peace negotiations between Israelis and Palestinians. Mitchell met Thursday with Israeli President Shimon Peres. He plans to meet Friday with Prime Minister Benjamin Netanyahu before talking with Palestinian leaders in the West Bank. A view from Egypt: Obama honor premature
Secretary of State Hillary Clinton was starting a six-day trip to Russia and Europe on Friday. On the trip, the secretary will discuss the next steps on Iran and North Korea, and international efforts to have the two countries end their nuclear programs.
The centerpiece of the trip will be her visit to Moscow, where she will work toward an agreement to take the place of the Start II arms control pact, which expires December 5. She also will address the new bilateral presidential commission that is working on a broad range of issues, from arms control to health.
"This is an encouragement to this president to continue to follow through on those commitments when, inevitably, he hits the bump in the road," said John King, CNN chief national correspondent .
"The committee is essentially saying, 'Stay at it, Mr. President. You have our prestige behind you now.' " Laureates to Nobel winners: Prepare for 'lightning bolt'
King noted that the Nobel Committee pushes "multilateralism around the world [and] very much disliked the prior U.S. president [George W. Bush]. ... This is in part a reflection of that as well."
Bush was heavily criticized during his presidency for what some observers said was an excessive reliance on unilateral action and U.S. military power.
In a statement announcing its decision, the committee said that multilateral diplomacy "has regained a central position, with emphasis on the role that the United Nations and other international institutions can play. Dialogue and negotiations are preferred as instruments for resolving even the most difficult international conflicts." Obama unique among presidential Nobel winners
The decision of the international committee to award Obama the prize highlights the sharp contrast in views toward the president at home and abroad. Watch how online community reacted »
Obama remains extraordinarily popular overseas, particularly in Western Europe. A recent Pew Research Center survey found that more than three-quarters of respondents in Britain, Germany, France and Spain approve of Obama's foreign policy.
In the United States, however, Obama's overall approval ratings have declined. An October 1-5 Associated Press poll showed that 56 percent of Americans approved of Obama's job performance. A September 17-20 NBC/Wall Street Journal poll found that only half of all Americans backed his handling of foreign policy.
The split perception was illustrated earlier this year by a U.S. university's decision to deny Obama an honorary degree when he delivered a commencement address at the school. While the Nobel Committee on Friday praised Obama for his "extraordinary effort," a spokesman for Arizona State University said last spring that Obama's "body of work is yet to come. That's why we're not recognizing him with a degree at the beginning of his presidency." Watch John McCain's reaction to Obama being awarded prize »
The last sitting U.S. president to win the peace prize was Woodrow Wilson in 1919. The other was Theodore Roosevelt in 1906. Jimmy Carter had been out of office for more than two decades when he won in 2002.
This year's Peace Prize nominees included 172 people -- among them three Chinese dissidents, an Afghan activist and a controversial Colombian lawmaker -- and 33 organizations, the highest number of nominations ever.
The Nobel recipient receives a prize of about $1.4 million. Obama plans to donate the money to charity, a White House spokesman said.
CNN's Dan Lothian contributed to this report.