Nepal's parliament speaker has announced that members will vote Sunday to choose a new prime minister of this Himalayan nation.

Speaker Subash Nemwang announced Friday that candidates will be able to file nominations on Saturday. A candidate will have to secure a simple majority to win.

The current prime minister, Sushil Koirala, is stepping down as required by the new constitution that was adopted last month.

Protesters unhappy with the new constitution have been protesting in southern Nepal, causing highways and border points to be closed.