WASHINGTON (AFP) - The United States is increasingly convinced Syrian President Bashar al-Assad will be overthrown and is preparing for a possibly violent aftermath, the New York Times reported Tuesday. The newspaper said Washington is quietly working with Turkey to plan for a post-Assad future that could see Syrias various ethnic groups battle for control of the country, potentially destabilizing neighboring states. It said that despite calling on Assad to step down, the United States has yet to withdraw its ambassador, Robert Ford, because it views him as a vital conduit to the opposition and various ethnic and religious communities. The Times said intelligence officials and diplomats in the Middle East, Europe and the United States increasingly believe Assad will not be able to quash the months-long revolt against his familys four-decade-long rule. Theres a real consensus that hes beyond the pale and over the edge, the Times quoted a senior official in US President Barack Obamas administration as saying. Intelligence services say hes not coming back. Assad has deployed tanks and troops in an increasingly violent response to anti-regime protesters inspired by the Arab Spring, with at least 2,600 people, mostly civilians, killed since March 15, according to UN figures. Obama was to discuss the Syrian crisis and wider turmoil throughout the Middle East in talks on Tuesday with Turkish Prime Minister Recep Tayyip Erdogan on the sidelines of the UN General Assembly.