A supporter of Nepali Congress party cheers while holding a party flag as leads by their candidates are displayed on a screen outside a vote counting center in Katmandu, Nepal
Veteran politician Sushil Koirala was expected to become Nepal's new prime minister after a rival political party announced its support on Sunday, ending months of deadlock following last year's elections.
Parliament will convene on Monday to vote for a premier, paving the way for the formation of a government charged with ending a prolonged political crisis that has crippled the economy.
Koirala, 75, is expected to be the only candidate after his Nepali Congress party -- which topped the polls last November -- secured the backing of the Unified Marxist-Leninist party (UML), which came second.
UML chairman Jhalanath Khanal said his MPs would vote for Koirala, following extensive negotiations within the party and with Nepali Congress on the make-up of the new coalition government.
"Our party has decided to support Nepali Congress in the election for the prime minister," Khanal told reporters.
"The details of the deal will be out soon. Everything will be agreed on a package. We are also discussing the new government's policy and programme," Khanal said.
Nepal held elections on November 19 for a constituent assembly or parliament, charged with writing a constitution aimed at bringing stability to a country still divided by the legacy of a decade-long civil war.
But a new government was not formed, amid a row within Nepali Congress over who should be prime minister.
The party had also become bogged down in negotiations with other parties on forming a coalition.
Nepali Congress finally chose Koirala last month as its candidate following a vote by its legislators.
The party won 196 seats last November and the UML secured 175. The Maoists were relegated to a humiliating third place with just 80 seats.
The Maoists, who traded their guns for politics after signing a pact to end the civil war in 2006, initially claimed fraud.
But they agreed in December to join the assembly after securing a pledge from the other parties for an inquiry into their claims.
The Maoists came to power in 2008 after a landslide election victory, two years after signing a deal to end the insurgency which also saw the abolition of the 240-year-old monarchy.
But the ensuing four years were marked by a series of short-term coalition governments, mainly led by the Maoists. The first assembly broke up amid rancour in May 2012.
Nepal has been in political limbo since then.
The new parliament held its first meeting last month. Leaders from across the political divide vowed to draw up the constitution within a year as promised to the people.