CARACAS, Nov 22 (Reuters) - Venezuela"s opposition needs to rebuild and reflect on its strategy after suffering a heavy defeat in regional elections at the weekend, its leader Juan Guaido said on Monday, calling for unity among the fragmented movement"s leadership. Venezuela"s National Electoral Council (CNE) awarded victory in 20 gubernatorial races to the ruling Socialist party and said opposition politicians had won only three, including the western oil-rich state of Zulia, according to initial results on Sunday. The main opposition parties had boycotted presidential elections in 2018 and congressional polls in 2020, arguing a fair ballot was impossible because of interference from President Nicolas Maduro"s government and violent gangs loyal to him. But they returned to the ballot box this year amid frustration over the failure of U.S. sanctions to dislodge Maduro despite prolonged social and economic hardship. Sunday"s vote were seen as a test of strength ahead of presidential elections scheduled for 2024. The opposition was also emboldened by the presence of election observers from the European Union. A preliminary report from the mission is due on Tuesday, but there were no major reports of disruptions. Guaido, the former speaker of Congress who is recognized by Washington and its allies as Venezuela"s rightful leader, said on Monday that the opposition needed to "rebuild itself" after the disappointing result. "Today a new phase is opening," he said, without providing specifics. "Today is a time for reflection amongst our leadership... It is not the time for fights nor egotism among political leaders." Analysts said ahead of the vote that the opposition"s late decision to participate and in-fighting over whether it should run candidates would damage its showing. The opposition urgently needed to rethink its strategy in order to reconnect with voters and burnish its credibility, said Enderson Sequera, head of Venezuela"s Politiks consultancy. "The conclusion of (Sunday"s vote) in Venezuela is very clear: Chavismo is more stable in power and the democratic opposition finds itself further from achieving political change," Sequera said, referring to the nickname for the ruling party, once headed by the late President Hugo Chavez. NEED TO REBUILD TRUST Despite opposition efforts to galvanize voters at the last minute, turnout was relatively low at 41.8%, according to the CNE. That is equivalent to some 8.1 million people and is in line with previous local and regional elections. Low turnout in Venezuela favors the ruling Socialist party"s political machine, analysts say. "The government has shown again that despite not having widespread popular support, it remains in power due to the lack of an opposition with a coordinated strategy," said Maryhen Jimenez, a researcher at the University of Oxford"s Latin American Centre. After seeing living standards decline amid hyperinflation and a seven-year recession, many ordinary Venezuelans are disillusioned with politics. Millions of people have emigrated. Though the ruling party won the 20 gubernatorial seats, their number of supporters decreased to 3.7 million, according to CNE figures, compared to some 5.9 million votes of support in 2017 regional elections. The CNE has yet to announce victors in mayorship races - with the exception of capital Caracas, where the ruling party candidate won. Maduro said on Sunday a return to negotiations in Mexico with the Venezuelan opposition would not take place until "the kidnap" of prominent government envoy Alex Saab - recently extradited to the United States on money laundering charges - is answered for. The talks, begun in August, are meant to seek a way out of Venezuela"s economic and social crisis. Guaido said he was cautiously optimistic the government would return to the table and he was discussing with international allies ways of increasing pressure on Maduro"s government.