Lawyers for the imam living in Pennsylvania whom Turkish authorities accuse of directing a coup last month in that country said Friday they fear for his life and may ask U.S. authorities to help protect him.

Since the failed coup that led to the deaths of 271 people, Turkish President Recep Tayyip Erdoganhas accused the imam, Fethullah Gulen, of issuing instructions to launch the coup, a charge Mr. Gulen has denied.

Turkish authorities have demanded the U.S. extradite Mr. Gulen immediately to Turkey, but The Wall Street Journal reported Thursday that U.S. officials don't expect to do that, citing people familiar with the discussions. U.S. officials see problems with the evidence presented thus far by Turkey, and they are concerned about strident public statements made by Turkish leaders against Mr. Gulen, those people said.

Mr. Erdogan has called Mr. Gulen and his supporters a terrorist network, a charge U.S. officials have long discounted. Turkey in May officially designated Mr. Gulen’s network a terrorist organization, making membership a crime under Turkish law.

Mr. Erdogan’s government has pressed the Obama administration since the coup to extradite Mr. Gulen, arguing that pursuing the imam is part of the broader campaign against terrorism. At times, the Turkish leader’s aides have said Ankara would view as hostile any foreign government that gave sanctuary to leaders of the Gulen movement.