Nepal Prime Minister Sushil Koirala resigned on Saturday ahead of the election for the post on Sunday.
He tendered his resignation to President Ram Baran Yadav on Saturday, his office said.
Koirala, president of the largest party, Nepali Congress, was elected in February 2014. Under his leadership, Nepal successfully promulgated a new constitution.
The party decided to again field Koirala for the post and will register his candidacy on Saturday itself.
Chairman of the CPN-UML, K P Oli, has already registered his candidacy. Once Koirala also does so, there will be a straight fight for the post.
