Binod Joshi / AP Ram Baran Yadav, a physician from the Madheshi ethnic community in southern Nepal, was elected as the republic's first president in Katmandu on Monday.

KATMANDU, Nepal — Nepal's governing assembly elected the country's first president Monday, rejecting a candidate backed by former Maoist rebels and creating political uncertainty for the new republic.

The Constituent Assembly elected Ram Baran Yadav, a physician from the Madheshi ethnic community in southern Nepal, which has been campaigning for greater rights and more say in the administration, assembly Chairman Kul Bahadur Gurung announced.

Yadav's victory was a blow for the Maoists, who won the most seats in the assembly in April elections and hope to form the country's new government, with one of their members as prime minister. But they first need to form a coalition government since they failed to win a simple majority in the assembly.

The assembly was elected in April after the dissolution of the monarchy and is supposed to rewrite the constitution and govern the nation.

The presidency is a largely ceremonial post, but the decision by the country's three top opposition parties to back a non-Maoist candidate for the job threatens to undermine coalition negotiations.

"We have been forced to change our plans to form the new government. We have to rethink our plans because of the new developments, which have ended the basis for further agreements with the other parties," said Chandra Prakash Gajurel, a senior leader of the Communist Party of Nepal (Maoist).

Gajurel said a formal decision will be made during the party's central committee meeting today.

Yadav, of the Nepali Congress Party, won 308 votes, giving him the required majority of votes cast by the 594-seat assembly.

Maoist candidate Ramraja Singh received 282. Six members were not present.

Yadav was backed by his party, the Communist Party of Nepal (United Marxist-Leninist) and the Madhesi People's Rights Forum — the second-, third- and fourth-largest parties.

Yadav has served twice as health minister and has been elected twice to parliament.

He received the most votes in the initial voting for president on Saturday, but none of the three candidates was able to secure the required majority. A second round of voting was held Monday with the top two candidates from Saturday's election.

Maoists gave up their armed revolt in April 2006 to join the peace process after 10 years of insurgency that left more than 13,000 people killed. They joined parliament and the government later and contested the April 10, 2008, election for the assembly.

They won the most seats in the assembly but were not able to secure a majority.

The last king, who went by just one name, Gyanendra, was forced to give up authoritarian rule in April 2006 after weeks of pro-democracy protests, and his powers were stripped soon afterward.

He has been made to leave the royal palace and now is living as a commoner in a summer home just outside the capital Katmandu.