VIENNA - The United States, Russia and other regional and world powers were considering a new plan Friday to set up a ceasefire in Syria within the next four to six months, followed by the formation of a transition government featuring President Bashar Assad and opposition members, officials told The Associated Press.

How long Assad could remain in power under the transition was still unclear.

The Western officials said the United States and its partners supported the timetable as a first phase toward ending the four-and-a-half year civil war that has killed more than 250,000 people and uprooted more than 11 million, leading to the growing terrorist threat of the Islamic State and sparking a refugee crisis throughout Europe. They said an agreement hadn't yet been reached, but that the 19 nations meeting in Vienna were considering the idea.

The officials, who spoke on condition of anonymity because they weren't authorized to speak publicly on the matter, said that a follow-up meeting was expected as early as next week, with top diplomats possibly returning to Austria's capital.(AP)