Salvadoran presidential front-runner Nayib Bukele of the Grand National Alliance for Unity. (AP Photo/Moises Castillo)

Salvadorans have watched as internationally sponsored investigative bodies in neighboring Guatemala and Honduras brought high-profile cases that took down corrupt politicians and businesspeople. Nayib Bukele wants to give his compatriots their own version of that.

Bukele, a young businessman and former mayor of El Salvador's capital, is the front-runner in Sunday's presidential election and polls indicate his focus on fighting endemic graft has him well positioned to break the hold of the two parties that have dominated the government for three decades.

If elected, the 37-year-old promises the creation of a Commission Against Impunity in El Salvador, or Cicies for its initials in Spanish. He says he hopes to secure support from abroad for such an effort, as has been the case for Guatemala (the United Nations) and Honduras (the Organization of American States).

“We have said it loud and clear: Regardless of whether it involves someone from our party or any other party, whoever it is, the Cicies will have to act against a corrupt person,” Bukele told The Associated Press in an interview this week.

He is the only one of four candidates on the ballot to make such a promise.

Bukele made his political debut in 2012 with the ruling FMLN party, which arose from a leftist guerrilla movement after peace accords ended El Salvador's civil war. He was elected mayor of the small municipality of Nuevo Cuscatlan, then three years later he won the mayoralty of San Salvador.

But his frequent public criticism of the FMLN and current President Salvador Sanchez Ceren led to his expulsion, accused of violating party principles.

Today he is the standard bearer of the Grand Alliance for National Unity — its initials, GANA, mean “win” in Spanish — and is challenging the political dominance that has reigned since the peace accords.

A recent poll gave him support from about 40 percent of Salvadorans, compared with 23 percent for businessman Carlos Callejas of the conservative Arena coalition. He was even further ahead of the FMLN's Hugo Martinez, a former foreign minister.

El Salvador's last six presidents have come from either Arena or FMLN.

Three of them have been accused of corruption: Arena's Francisco Flores (1999-2004), who died while under house arrest; Tony Saca (2004-2009, also from Arena), who last year pleaded guilty to embezzling hundreds of millions in government funds; and the FMLN's Mauricio Funes (2009-2014), now a fugitive in exile in Nicaragua, wanted for purportedly diverting $350 million.

So it's perhaps unsurprising that Salvadorans respond to Bukele's vow that eliminating graft is essential to moving the country forward. He has campaigned on the slogan of “There will be enough money when nobody steals,” and says Cicies would investigate corruption dating back three decades — 20 years when Arena was in charge, and the last 10 under the FMLN.

“It is clear that there has been money, but it has gone to line the pockets of the corrupt,” Bukele said.

In their harshest assessments, Bukele's rivals and critics suggest he could be trouble. Miguel Fortin Magana, who leads a movement called Libertad, or “freedom,” accuses him of being “narcissistic and megalomaniacal” and calls him “the only presidential candidate who is dangerous.”

Martinez has criticized Bukele for avoiding debating publicly, accused him of not being willing to answer uncomfortable questions and questioned whether that could have negative implications for a free press.

Political analyst Alvaro Artiga said polls have favored Bukele for over a year but it remains to be seen exactly how that will play out in the vote. To his mind, the candidate evinces “a rejection of control” for his public criticisms of institutions such as the Supreme Electoral Tribunal and the Attorney General's Office.

Bukele said he hopes to model Cicies on the International Commission Against Impunity in Guatemala, which has come under fire from Guatemalan President Jimmy Morales since it pushed several investigations targeting him, family members and associates. Morales denies any wrongdoing.

Bukele said he has not spoken to the United Nations but has had conversations with the OAS's secretary-general. He did not give details.

On foreign relations, Bukele said he would promote strong ties with the United States and also examine all deals between the current government and China. Last year Sanchez Ceren switched El Salvador's diplomatic recognition from Taiwan to Beijing, a move that prompted Washington to recall its ambassador.

“We have to review that deal this outgoing government made at the last minute in exchange for some tons of rice,” Bukele said. “We are going to review it, but we will not necessarily break relations with China.”

Bukele also had strong words for Venezuela and Nicaragua, two countries with governments accused of increasing authoritarianism and repression of dissent.

“For us the government of [Venezuelan Nicolas] Maduro is not a government that allows democratic plurality,” Bukele said. “It does not allow for there to be a real opposition, and that is not democratic.”

Under Sanchez Ceren, El Salvador has been one of the countries in the region backing Maduro during Venezuela's political crisis, even as the U.S., Brazil, Canada, Argentina and other nations recognized the head of the opposition-controlled congress as interim president in a challenge to Maduro's power.

As for Nicaragua, Bukele said he could not remain quiet while “seeing that hundreds of young students have been murdered by the regime of [Daniel] Ortega, a president who says he is from the left but is no different from [Anastasio] Somoza, the dictator they kicked out — now he is doing the same thing.”

Bukele argued that he has an advantage over his rivals in condemning what he sees as anti-democratic actions, “because we are not bound to these governments.”

Bukele studied law at Jose Simeon Canas Central American University but left before getting a degree. At 18, with support from his father, he founded a publicity agency.

He is married and awaiting his first child. Born to a Roman Catholic mother and a Muslim father, he proclaims his belief in God but not organized religion.

If no candidate wins a majority Sunday, a runoff will be held.

Marcos Aleman reports for the Associated Press.