Five nations abstained on the vote, including Russia and China. But the fact that neither exercised their right to veto the resolution represented a major victory for the U.S. and its allies, who've often been stymied at the global body by countries fearful of granting powers that infringe on national sovereignty.
For Obama, the shift to international action comes as he faced increased criticism for not moving aggressively enough to help the rebels trying to topple Gadhafi, long counted as among the world's most ruthless dictators. Some U.S. lawmakers demanded the no-fly zone, while others have proposed more strident measures such as supplying the opposition with arms.
Three leading senators applauded the U.N. action.
"The administration deserves credit for getting this resolution passed with such strong support," said a joint statement from Sen. John Kerry, D-Mass., John McCain, R-Ariz., and Joe Lieberman, I-Conn. "This was an important step on behalf of the people of Libya, but it will only be as effective as its implementation. With Gadhafi's forces moving toward Benghazi, we must immediately work with our friends in the Arab League and in NATO to enforce this resolution and turn the tide before it is too late."
The senators said they would also work to build bipartisan support for Obama to take "decisive measures to stop Gadhafi."
That backing was missing Thursday at a Senate hearing, as Sen. Marco Rubio, R-Fla., and others criticized Obama and his national security aides for moving too slowly to cut off the Libyan government's counteroffensive. Initially rocked by the revolt, the regime has recently regained lost territory and set its sights on Benghazi, the last rebel stronghold.
William Burns, undersecretary of state for political affairs, said Gadhafi's forces "have made significant strides on the ground over the course of the last 24, 48 hours ... taking full advantage of their overwhelming military."
Ahead of the U.N. vote, several lawmakers hinted that a change in the U.S. approach might be coming.
"If they (the rebels) can hold out another week, that may be the time necessary for the international community to respond," Sen. Mark Kirk, R-Ill, told reporters.
Sen. Lindsey Graham, R-S.C., said he believes President Barack Obama has authority to commit U.S. forces to participate in the no-fly zone without congressional approval, but he expressed hope that Congress would bless the move.
"If the Obama administration decides to impose a no-fly zone or take other significant military action in Libya, I believe it should first seek a congressional debate on a declaration of war."