Rebels in Haiti are threatening to "liberate" the capital if President Jean-Bertrand Aristide does not step down.

New rebel leader Guy Philippe has urged the international community Thursday, to convince Mr. Aristide to resign quickly -- or else the rebels will take over the presidential palace in Port-au-Prince and other cities.

Leaders from the Organization of American States are set to meet later Thursday in Washington to discuss the two-week-old armed uprising against the government. The rebels, now called the Front for the Liberation and National Reconstruction of Haiti, have already taken over a dozen cities and towns. More than 55 people have been killed in the revolt.

Earlier Thursday, U.S. Secretary of State Colin Powell said the United States, Canada, France, the United Nations and others are working on a plan for a political solution to the conflict. He said the proposal at this point does not include calls for President Aristide, an elected leader, to step down before his term ends in 2006.