Here are some facts on the four contenders:

ANDRES MANUEL LOPEZ OBRADOR

Two-time presidential runner-up Andres Manuel Lopez Obrador, known as AMLO, enjoys a more than 20-point lead in most polls, running on an anti-corruption platform with his National Regeneration Movement (MORENA) party.

The former Mexico City mayor has capitalized on widespread anger over years of rampant corruption and violence, but has been vague on policy details. Seeking to corral support from economic nationalists, leftist liberals and social conservatives, he has pledged to combat inequality, improve pay and welfare spending, as well as run a tight budget.

He could usher in a Mexican government less accommodating toward the United States, where U.S. President Donald Trump has stoked trade tensions with Mexico and aggressively moved to curb immigration.

Variously described as a leftist, a populist and a nationalist, Lopez Obrador, 64, has used the slogan "peace and love" during the campaign and has deployed a team of aides to reassure Wall Street that he will not roil the economy.

But he has also promised to review recently awarded oil contracts and threatened to cancel Mexico City's new airport, while criticizing individual business leaders whom he accuses of being part of the "mafia of power."

When he narrowly lost his first presidential bid in 2006, he contested the result and organized a sit-in that closed one of the main thoroughfares in Mexico City, the capital, for weeks, causing chaos.

Lopez Obrador, whom his critics accuse of being a destructive socialist like former Venezuelan President Hugo Chavez, says he has changed since then. On the current campaign, he has appeared less easily upset, regularly making light of his opponents' attacks.

RICARDO ANAYA

The youngest of the four presidential candidates, the 39-year-old Anaya sprang to prominence when he took over the presidency of the conservative National Action Party (PAN) in 2015.

Born in the wealthy, central state of Queretaro, the career politician helped the party take more than 10 of the country's governorships for the first time in its history.

His main proposals include increasing the minimum wage, raising public spending to reach 5 percent of gross domestic product by 2021, and forming an international commission to investigate the current government over corruption allegations.

He has also indicated he would take a firm line with Trump.

As the U.S. president imposed steel tariffs on Mexico, Anaya responded on Twitter in English: "Let us be clear, @realDonaldTrump: it is a lie that Mexico doesn't do anything to help the USA. Mexico helps the USA too much."

Anaya has been criticized for his frequent trips to Atlanta, where his wife and three children have lived, and was hurt in the polls by a real estate deal the ruling party said was money laundering.

Anaya denied the allegations.

He joined the PAN as a law student and held several senior positions in the Queretaro state government between 2002 and 2009 before becoming president of the lower house of congress in 2013.

JOSE ANTONIO MEADE

At the end of 2017, in an attempt to clean up its image and as Lopez Obrador took off in opinion polls, the ruling Institutional Revolutionary Party (PRI) chose a non-member as its candidate for the first time.

Meade, 49, has served in five different ministerial jobs, including foreign affairs, social development, energy and finance, under PRI and PAN governments.

During the campaign he said he would expand the conditional cash transfer program "Prospera" to include 2 million more families. Has also vowed to extend social security to cover domestic workers.

Meade led a campaign to strip politicians of immunity but has been unwilling to criticize outgoing President Enrique Pena Nieto, whose PRI government has faced multiple corruption allegations.

Meade's critics blame him for a hike in gasoline prices in 2017 that led to protests across Mexico and spiked inflation, and tie him to corruption accusations at departments he ran. He denies any wrongdoing.

JAIME RODRIGUEZ

Known as "El Bronco," Jaime Rodriguez is the only independent contender left in the race, and polls estimate he will get between 1 and 6 percent of the vote.

He shocked voters in one of the televised debates when he advocated chopping off the hands of those who steal — including public servants.

The on-leave governor of Nuevo Leon has also railed against social handouts and said he would get rid of the government department tasked with eliminating poverty. Rodriguez says it does not combat poverty but increases it.

In May, Mexico's electoral authority, INE, fined Rodriguez for allegedly raising almost $700,000 in illicit campaign funds. Rodriguez denied wrongdoing. He is the only candidate who has declared any private financial donations.

(Graphic on Mexico's presidential election: tmsnrt.rs/2MVhfjA)

(Graphic on Latin American elections: tmsnrt.rs/2rAQ4l1)