NATO has launched around-the-clock surveillance flights of Libya.

Representatives of key Western powers also highlighted the possibility of establishing a no-fly zone in Libya -- part of growing campaign to break strongman Moammar Gadhafi's grip on power.

British, French and U.S. officials were working on a draft text that includes language on a no-fly zone, diplomatic sources at the United Nations told CNN.

The language in the text will deal with triggers rather than timelines for taking such a step, one diplomat noted. If gross violations of human rights are committed, the diplomat added, the elements of the text could be quickly turned into a resolution.

Any resolution on military intervention in Libya, however, would be subject to a vote by the 15 members of the U.N. Security Council. Such intervention could face sharp criticism from Russia and China, who rarely approve of such measures.

Obama stressed that NATO is considering a wide range of responses -- including military options -- for dealing with the crisis.

White House Press Secretary Jay Carney later cited three potential responses under active consideration: establishing the no-fly zone, military-backed humanitarian aid, and stronger enforcement of the U.N. arms embargo.