El Salvador's President Nayib Bukele looked set to increase his power as his allies took a clear lead in legislative elections, according to preliminary results Monday.

"Victory," Bukele tweeted in anticipation of a win, along with a video of fireworks in the capital San Salvador.

The New Ideas party, founded by Bukele and running for election for the first time, together with the Grand Alliance for National Unity (GANA), through which he came to power, had well over half the votes according to the Supreme Electoral Tribunal (TSE), with almost 90 percent of ballots counted after Sunday's elections.

Bukele, 39, is a harsh critic of the traditional parties, whom he accuses of abandoning the victims of the 1980-92 civil war.

His detractors accuse him of authoritarianism.

The official count will only begin on Tuesday, when it will be determined how many of the 84 seats in Congress each party will take.

Bukele also shared results of an exit poll by Costa Rican firm Cid Gallup which gave New Ideas a large majority in parliament, with more than 67 percent of the vote, although technical details of the survey were not released.

"New Ideas + GANA will have more than 60 deputies... Thank you to the Salvadoran people. Thank God," he tweeted.

El Salvador's President Nayib Bukele uses social media to his advantage and has cultivated an image as a man of the people
El Salvador's President Nayib Bukele uses social media to his advantage and has cultivated an image as a man of the people AFP / STANLEY ESTRADA

If the results are confirmed, Bukele could fulfill his objective of winning an absolute majority in parliament, which would give him more power over crucial decisions and lawmaking.

The victory "will leave little room for the remnants," said analyst Oscar Picardo, of Francisco Gavidia University.

Bukele hopes to have his hands untied after a frustrating two years of blockages by an opposition-controlled parliament.

Long queues of voters wearing face masks amid the coronavirus pandemic formed well before voting started, though many stations opened hours late.

The delay prompted Bukele to level accusations of wrongdoing against the TSE on Twitter.

"We told them 1,000 times that, whether through corruption or incompetence, they would do everything wrong," he said.

President Bukele's allies were in the lead according to partial results after Sunday's election
President Bukele's allies were in the lead according to partial results after Sunday's election AFP / MARVIN RECINOS

But an election observer told AFP he had seen no evidence of voter fraud.

About 40,000 police, soldiers and international observers were deployed to oversee the balloting, which came after the worst political violence in years claimed two lives last month.

After polls closed, the Organization of American States described election day as peaceful.

The TSE said 51 percent of the country's 5.4 million voters cast ballots to elect 84 members of the Legislative Assembly from among 10 political parties.

Elected in 2019 for a five-year term, Bukele, who is 39 and is of Palestinian and Greek descent, has had trouble getting some programs approved in a parliament dominated by two opposition parties -- the right-wing Arena and leftist FMLN.

Neither party "has managed to resolve their serious corruption problems," said Picardo.

Bukele has vowed to tackle the country's two most notorious gangs: Barrio 18 and MS-13 (Mara Salvatrucha), the second of which has been designated a terrorist organization by the United States.

Until 2019, El Salvador was considered one of the most violent countries in the world not actively at war, but Bukele managed to reduce the murder rate.

He has the support of the security forces both to deliver food to people, and to help him flex his muscles.

In February 2020, in a bid to intimidate MPs into approving a loan to finance an anti-crime plan, the president ordered heavily armed police and soldiers to storm parliament.

When lawmakers recently called for a congressional committee to declare Bukele "mentally incapable" of governing, he denounced it as an "attempted parliamentary coup."

Since a 1992 peace deal ended more than a decade of civil war, no party has won an absolute majority in parliament.

If Bukele does so, he would be able to appoint judges to the Supreme Court and the public prosecutor's office -- institutions with which he has clashed.

But Geoff Thale, director of the Washington Office on Latin America, warned that "maintaining the independence" of other branches of government will be "critical."

Polls predict victory for Bukele backers in the vote for 262 mayors and for El Salvador's 20 representatives to the six-nation Central American Parliament.