By Gopal Sharma

KATHMANDU (Reuters) - Nepal's Maoist Prime Minister Baburam Bhattarai promised on Wednesday to hold delayed elections in May, raising hopes for an end to a political stalemate that has crippled the Himalayan republic still emerging from a decade-long civil war.

A former rebel leader, Bhattarai announced the polls to a rally of 10,000 cheering, flag-waving supporters in the heart of the Nepali capital. It was a show of strength after weeks of violent street protests by opposition parties demanding the prime minister's resignation.

Nepal's parliament was dissolved in May, having failed to reach a consensus on drafting a new constitution seen as central to long-term stability. Since then, opposition parties have pressured Bhattarai to quit to pave the way for the formation of a national unity government to oversee elections.

The polls had initially been set for last November, but they were deferred as opposition parties refused to cooperate, saying the dates, finalized without consulting them, were impractical.

"We are committed to hold the election in May. There is no alternative to this," Bhattarai said.

An alliance of nine opposition parties has launched often violent demonstrations in recent weeks and clashed with the Maoists, injuring dozens. Opposition parties have vowed more protests until Bhattarai stands down. He has so far refused.

Earlier this week, opposition activists stoned the prime minister's convoy in west Nepal, while he was going to attend a party conference.

ELUSIVE CONSENSUS

To be able to hold the election, political parties must first agree on a date, update the voters' list, change election-related laws and appoint election commissioners, all of which needs a cross-party consensus that has proved elusive so far.

Nepal's Election Commission has said it needs at least 120 days to prepare for the vote, leaving the parties with little time to meet the May deadline before the onset of annual monsoon rains makes the exercise difficult in the mountainous nation.

"Holding timely elections is a political, constitutional and democratic obligation for Nepal's political leadership," former U.S. President Jimmy Carter has said in a article in the Kathmandu Post newspaper.

"Nepal's political leaders should take this precious opportunity to move boldly and with courage to hold elections in spring 2013 and to energize the peace process once more," wrote Carter, whose Carter Centre has observers monitoring the peace process.

The deadlock over the polls has spooked investors and slowed foreign aided development projects. About 1,600 frustrated young Nepalis leave every day in search of menial work in the Middle East, Malaysia and Korea.

"The absence of parliament for a long time has resulted in the lack of transparency and accountability in the government," a Western diplomat said. "I think political parties must realize this on time and agree on early elections," he said.

The Maoists waged an armed struggle against the country's now toppled monarchy. They joined the political mainstream in 2006 after the end of the civil war that killed more than 16,000 people. They won elections two years later and are now leading a coalition government in the impoverished Himalayan republic.

(Editing by Matthias Williams and Alison Williams)