Lawyers for US-based Turkish cleric Fethullah Gulen say they fear an attack on his life, in the wake of the failed coup attempt on 15 July in Turkey.
Turkey has issued an arrest warrant for Mr Gulen, accusing him of orchestrating the coup attempt. It has called on the US to extradite him.
Mr Gulen denies any involvement.
Turkey has cracked down heavily in the wake of the coup attempt. On Friday the governing AK Party ordered an internal purge of Gulen supporters.
More than 270 people died in events surrounding the coup attempt.
Speaking at a news conference in Washington, Mr Gulen’s lawyers said they expected him to remain at the Pennsylvania compound where he lives in self-imposed exile, and not attempt to flee.
Mr Gulen is a reclusive figure who rarely makes contact with the media.Mr Gulen’s lawyers said it was unlikely any extradition request would stand up in a US court and there was almost no chance that their client would get a fair trial in Turkey, given what had been said against him there since the coup attempt.
One of the lawyers, Reid Weingarten, said: “It would be unprecedented and appalling if the United States took a frail almost-octogenarian, plopped him on a plane to go back into that kind of setting with the hideous things that are being said about him by the entire Turkish government.”
Much of Turkey’s crackdown has targeted perceived supporters of the cleric.
Tens of thousands of public sector workers have been suspended or dismissed, with many having their passports cancelled. There has also been a massive reshuffle of the military.
About 18,000 people have been detained or arrested.
Now local branches of the AK Party have been told to begin a purge of suspected Gulenists in their ranks.
Mr Gulen had been a close ally of President Recep Tayyip Erdogan until a bitter split between his movement and the party of the president three years ago.
Turkey has listed Mr Gulen’s movement as a terrorist organisation.