President Obama on Friday offered only tempered support for Libya’s rebels and played down the feasibility of Western military intervention to aid their cause, raising questions about how far he is willing to go to help fulfill his declaration last week that Libyan leader Moammar Gaddafi “must leave.”

Obama’s cautious commitment to the rebel movement, which he said is “just getting organized” in its fight to end Gaddafi’s 41-year rule, mirrored the stance taken Friday by European leaders, who until now had been speaking more boldly than Obama on how best to assist Libya’s opposition.

At an emergency European Union summit, leaders declared that Gaddafi can no longer be considered Libya’s leader and must step down immediately. But they stopped short of formally recognizing the rebel movement or endorsing military action to support its armed struggle.

The international position left Libya’s opposition increasingly vulnerable to Gaddafi’s vastly more potent military, now rooting out rebel forces near Tripoli, the capital, and driving to retake eastern territory under opposition control. Government forces claimed Friday to have retaken the strategic oil port of Ras Lanuf, recently in rebel hands, as momentum continued shifting toward Gaddafi loyalists.

Obama declared last week that Gaddafi “must leave” after losing the legitimacy to govern the oil-rich North African nation, and he has imposed financial sanctions, deployed U.S. naval assets to help deliver humanitarian aid, and re-focused intelligence resources on Libya as a check against military atrocities.

Defending his approach, Obama said Friday that such steps are “slowly tightening the noose” on the Libyan leader, as the Treasury Department widened sanctions to include additional Libyan officials, Gaddafi’s wife and several of his children.

But Obama has spoken coolly about several proposed military options, including a no-fly zone to protect rebel-held territory. His director of national intelligence, James R. Clapper Jr., warned this week that Gaddafi would probably win unless the opposition received help from the outside.

‘Costs versus benefits’

The issue moves Saturday to the Arab League, which will meet in Cairo to consider a no-fly zone and decide whether to recognize the Libyan National Transitional Council, the rebels’ provisional government based in the eastern city of Benghazi. Obama and other leaders have said international support, in some form, must precede any military action in Libya.

“It is in the United States’ interest and the interest of the people of Libya that Gaddafi leave,” Obama said at his afternoon news conference. “And we’re going to take a wide range of actions to try to bring about that outcome.”

Obama, who inherited two wars in Muslim nations, added that “when it comes to U.S. military actions, whether it’s a no-fly zone or other options, you’ve got to balance costs versus benefits. And I don’t take those decisions lightly.”

As rebel havens shrink under government assault, the administration and its European allies face an increasingly complex military scenario on the ground that complicates any intervention.

Obama has warned about the dangers of a protracted stalemate on the ground, and human rights advocates are increasingly concerned that the Libyan government will consolidate its territorial gains through a reprisal campaign against rebel supporters.

President Bill Clinton was criticized for failing to act to stop the 1994 genocide in Rwanda and for waiting too long to intervene in the Balkans, doing so only during the late-chapter conflict in Kosovo.

Speaking Friday to the Women in the World conference in New York, Clinton said the United States should immediately enforce a no-fly zone over Libya, since the rebels have asked for the assistance.

“Gaddafi has internationalized the conflict himself by hiring people from other countries who do not give a rip about the Libyans,” Clinton said, referring to foreign mercenaries fighting alongside government forces. “So that’s why [the insurgents] said, ‘Just give us the chance to have a fair fight,’ and I, for whatever it’s worth, think that’s what we should do.”

Setback for Sarkozy

Other past administrations have struggled with what signal to send to popular uprisings, especially in the Arab world.

During the 1991 Persian Gulf War, President George H.W. Bush announced that “there is another way for the bloodshed to stop: And that is for the Iraqi military and the Iraqi people to take matters into their own hands and force Saddam Hussein, the dictator, to step aside.”

Two weeks later, thousands of Shiite Muslims in southern Iraq and ethnic Kurds in the north rose up against Hussein, only to be brutally suppressed when no international support arrived.

Neil Hicks, the international policy director for Human Rights First, said the Obama administration has been careful, as a result, not to directly encourage Libya’s rebels.

“They’ve promised very little, so I think the rebels should count on very little from the United States,” Hicks said.

But Hicks and others say it is important that Gaddafi be forced from power, although how to do so remains the challenge.

“If he stays, his potential to destabilize what has happened in Tunisia and Egypt is great, and he will continue to give support to rulers who are the worst of the worst,” Hicks said. “But if the United States becomes deeply implicated in the process of overthrowing Gaddafi, then it also bears responsibility for what becomes of Libya in the aftermath.”

The cautious position staked out by the European Union on Friday represented a setback for President Nicolas Sarkozy of France, who had pushed for a bold stand that would put Europe more actively on the rebel side.

France has advocated robust planning for military operations if necessary and if the U.N. Security Council approves. Sarkozy, explaining the E.U. stand, said what he and other leaders have in mind as the trigger for any military operation is large-scale use of Gaddafi’s military aircraft against civilian populations.

“What would people have said if Europe, even before thinking it over, had renounced all kinds of military action in Libya?” he said.

Cody reported from Brussels.