BEIRUT — Lebanon’s leading Sunni Muslim politician, Saad Hariri, re-emerged as a candidate for prime minister on Sunday when the businessman Samir Khatib withdrew his candidacy to lead the government.

Mr. Hariri quit as prime minister on Oct. 29 in the face of mass protests against an entire political class blamed for state corruption and for steering Lebanon into the worst economic crisis since its 1975-90 civil war.

Consultations on designating a new prime minister had been set for Monday, but on Sunday President Michel Aoun postponed those talks by one week, his office said. Mr. Aoun must designate the candidate with the greatest level of support among Lebanon’s 128 lawmakers.

Under the country’s power-sharing system, the prime minister must be a Sunni Muslim. Mr. Hariri has continued to govern in a caretaker capacity until a new prime minister is named.