US President Barack Obama has insisted that Libyan leader Muammar Gaddafi "step down from power and leave," his most explicit statement of support for rebels challenging Gaddafi's four-decade rule in a region convulsed by uprisings against authoritarian regimes.
"We will continue to send a clear message: The violence must stop. Muammar Gaddafi has lost the legitimacy to lead and he must leave," Obama said at a White House news conference with Mexican President Felipe Calderon on Thursday.
Obama also appeared to suggest that Gaddafi loyalists switch sides in support of the revolutionaries.
"Those around him have to understand that violence that they perpetrate against innocent civilians will be monitored and they will be held accountable for it," Obama said. "And so to the extent that they are making calculations in their own minds about which way history is moving, they should know history is moving against Colonel Gaddafi."
The US administration has been tempering tough talk on Libya with a dose of reality, explaining that even a no-fly zone to control the skies over the country would require a military attack. Two leading senators on defence matters responded on Thursday by urging a strong US stance aiding Gaddafi's opposition.