In a statement issued Sunday from Martha's Vineyard, where he's vacationing, Obama said the surest way for the bloodshed to end is for Moammar Gadhafi to relinquish power.
The president said, "The future of Libya is now in the hands of the Libyan people." The rebels seized control of much of Libya's capital, Tripoli, on Sunday.
Obama's statement came after a Sunday evening conference call with his national security team.
He promised to work in close coordination with the rebels and said the U.S. will "continue to insist that the basic rights of the Libyan people are respected."