SAN SALVADOR (Reuters) - Salvadorans voiced hope for a changed country on Monday after political outsider Nayib Bukele won a sweeping victory in the presidential election with a pledge to tackle the corruption and violence plaguing the Central American nation.

Presidential candidate Nayib Bukele of the Great National Alliance (GANA) and his wife Gabriela de Bukele gesture as they celebrate with supporters after the first official presidential election results were released in San Salvador, El Salvador, February 3, 2019. REUTERS/Jose Cabezas

Bukele, 37, a former mayor of the capital, San Salvador, won 53 percent of the vote with returns counted from 99.9 percent of polling stations, the national electoral tribunal said on Monday, allowing him to clinch the presidency in the first round of voting.

His emphatic victory in Sunday’s election was a stunning rebuke to the two political parties that had dominated El Salvador since its civil war, the ruling leftist Farabundo Marti National Liberation Front (FMLN) and its long-standing rival, the conservative Nationalist Republican Alliance (ARENA).

Bukele’s promises to modernize government and his dynamic use of social media have energized young Salvadorans, eager for an end to the economic stagnation, poverty and violence that have beset the nation of 6.5 million people following its vicious 1980-1992 civil war.

On the bustling streets of San Salvador, Juana de Calderon, a 38-year-old cook in a small restaurant, said she cast a vote for Bukele hoping to put a stop to corruption.

“We hope that he fulfills what he promised in the campaign,” she said while preparing empanadas, a savory pastry popular in Latin America. “If we voted for him, it’s because we want something new - to have a different country.”

Bukele’s two rivals from the FMLN and ARENA quickly accepted defeat on Sunday evening.

Bukele must now contend with U.S. President Donald Trump’s frequent threats to cut aid to El Salvador - as well as to neighboring Guatemala and Honduras - if they do not do more to curb migration to the United States.

Gang violence has made El Salvador one of the world’s most murderous countries in the past few years, driving Salvadorans to flee to the north.

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Among his campaign promises, Bukele, an avid social media user who snapped a selfie with supporters before declaring his win, said he would push infrastructure projects to limit migration.

He will face challenges, however, pursuing his reform agenda from a divided Congress and an onerous government deficit. Bukele’s allies have only 11 legislators in the 84-seat Congress.

Credit rating agency Fitch said on Monday that governability would be a challenge for Bukele and highlighted an increased risk of polarization between the president and Congress. It forecast only modest economic improvement this year.

TURNING AWAY FROM TRADITIONAL LEFT

Growing up, Bukele’s relatively wealthy family was sympathetic to the FMLN, the former leftist guerrilla army that became a political party at the end of the civil war.

But Bukele has turned away from Latin America’s traditional left, branding Venezuelan leader Nicolas Maduro and Nicaragua’s Daniel Ortega as well as conservative Honduran Juan Orlando Hernandez as dictators.

“A dictator is a dictator, on the ‘right’ or the ‘left,’” Bukele wrote last week on Twitter.

Although he was expelled from the FMLN in 2017, Bukele describes himself as from the left. As he sought the presidency, however, he joined a conservative party known as GANA, or “win” in Spanish.

Along with the goal of modernizing government, Bukele, who is set to take office in June, has proposed creating an international anti-corruption commission with the support of the United Nations, following similar committees in Guatemala and Honduras.

“We’ll create a (commission) ... so that the corrupt can’t hide where they always hide. Instead, they’ll have to give back what they stole,” Bukele said in January.