Former President Jimmy Carter said today that he's persuaded Bosnian Muslims and Serbs to move toward a negotiated settlement of the war by New Year's Day after implementation of a ceasefire Friday. Under the deal, announced by Carter at Sarajevo airport after two days of talks with leaders on both sides, U.N. peacekeepers would monitor the ceasefire and civilians would have free movement. Carter did not say, however, what would happen if no agreement is reached by the January 1 deadline. The plan aims for a renewable, four-month armistice and stipulates the two sides consider a peace proposal promoted by the United States, Russia, France, Britain and Germany that would give 51 percent of Bosnia to a federation of Muslims and Croats. Muslims already back that solution; Bosnian Serbs never have and are already calling it merely a "starting point" for the talks.