The Nepali Congress emerged as the largest party in the 2013 Constituent Assembly elections under Koirala 's leadership . He was elected leader of the Nepali Congress Parliamentary party securing 105 out of 194 votes against former Prime Minister Sher Bahadur Deuba 's 89 votes and on 10 February 2014 he was nominated as prime minister . During his tenure as prime minister , his government was criticized for its slow aid response to the April 2015 Nepal earthquake . A historic agreement among four major political parties was also made that year , which paved the way for a new constitution in the country . Honoring a pledge to stand down as prime minister once the new constitution came into effect , Koirala resigned on 10 October 2015 . He sought re-election but was defeated by Khadga Prasad Sharma Oli , leader of Congress ' former coalition partners CPN-UML
April 2015 Nepal earthquake
April 2015 Nepal earthquake
Sushil Koirala