Mexico City – Millions of voters have headed to the polls in Mexico, in what is being billed as the largest election in the country’s history.

More than 3,400 posts are up for grabs on Sunday, including the presidency and all the seats in the two houses of Congress.

Polling stations opened at 13:00 GMT. The last voting centres were set to close at 01:00 GMT on Monday.

Results are expected later on Monday.

Three issues have defined the landmark race: security, corruption and poverty.

Mexico has slipped to 135th out of 180 countries in the Transparency International Corruption index.

A 2018 poll showed that 64 percent of the country’s population believes the government isn’t doing enough to combat corruption, and many Mexicans are sick of a political class that has become synonymous with pocket-lining and impunity.

Many are also becoming increasingly concerned about the country’s crime rates. Last year was the most violent on record and 2018 is set to surpass that with four people killed every hour in the month of May alone, according to government figures.

Poverty levels are also topping voter’s minds. More than 50 million of the country’s 127.5 million people live below the poverty line. About one percent of the country’s population holds a third of its wealth, according to a 2017 study by CEPAL – a regional economic commission of the UN.

Concern over these issues has seemingly helped frontrunner Andres Manuel Lopez Obrador.

The frontrunner: Andres Manuel Lopez Obrador

Known as AMLO, Lopez Obrador finished the campaign just as he started it: with clear daylight between himself and his rivals.

Leftist frontrunner Andres Manuel Lopez Obrador of MORENA gestures while leaving the Palacio de Mineria [File: Reuters]

A silver-haired, left-leaning populist who wows supporters at rallies with promises to fight “the power mafia” and eradicate all graft, Lopez Obrador had a 22-point lead in an aggregate of the final opinion polls on June 27.

The 64-year-old spent time in both Mexico’s ruling Institutional Revolutionary Party (PRI) and the Party of the Democratic Revolution (PRD) before veering off to form his own party, the National Regeneration Movement (Morena).

Despite his long career in politics, he bills himself as an outsider, and promises to bring wholesale change to the country from the top down.

The veteran politician has effectively been campaigning for the presidency for more than 12 years, addressing nearly all of Mexico’s more than 2,000 municipalities at least twice.

His supporters regard him as a man of the people. His opponents view him as an authoritarian, who, after losing the last two elections, refused to accept the result, and who with his ambitious plans for the government spending could send the country down the path of crisis Venezuela.

Lopez Obrador has insisted that he will be able to fund all of his programmes simply by cutting out corruption. But analysts say he has not presented concrete details on how he plans to do that.

This has contributed to the sense that voting for him is a step into the unknown, according to political analyst Eric Magar of the ITAM University.

“This is a sort of bet to get rid of the old guys, not being sure exactly what the new guys intend to do and how new they are on the other hand,” Magar told Al Jazeera.

PAN’s Ricardo Anaya

Of the three candidates trailing Lopez Obrador, Ricardo Anaya is the closest.

Ricardo Anaya, presidential candidate for the National Action Party (PAN), takes a selfie [Alexandre Meneghini/Reuters]

A tech-savvy, 39-year-old conservative, Anaya has risen to the top of the National Action Party (PAN) with a reputation as a meticulous planner and cut-throat political operator.

The latter has won him the candidacy of a left-right coalition, but cost him the support of some within his own party.

Anaya has said he will fight poverty with monthly payouts for all Mexicans and will also fight corruption. That message has been undermined, however, by allegations of money laundering – accusations he has denied and said are part of a smear campaign by the PRI.

PRI’s Jose Antonio Meade

The PRI’s candidate is in third place, according to opinion polls.

Jose Antonio Meade greets supporters during a campaign rally [File: Alberto Puente/Reuters]

Jose Antonio Meade Kuribrena has been portrayed as an affable and experienced political operator. He has held positions in the last two administrations.

The party has governed Mexico for 77 of the last 89 years, in the process becoming synonymous with corruption and inside dealing.

Many Mexicans say they simply won’t continue having the PRI in power for another six years.

Jaime Rodriguez Calderon

Coming last in the opinion polls is Jaime Rodriguez Calderon, an independent candidate.

Rodriguez Calderon in Mexico City [File: Gustavo Graf/Reuters]

He has branded himself as “El Bronco” or the wild horse.

The northerner was the first independent to become a governor in Mexico.

Calderon would like to be seen as a straight-talking maverick, but instead has been widely ridiculed for suggesting in the first presidential debate that the answer to corruption was cutting the hands off public servants who steal.

Electoral violence

Despite the focus on the presidential elections, other are keeping a close watch on the local mayoral races.

Among them, Mexico’s multitude of criminal gangs.

Public security policy consultancy firm Etellekt has counted more than 130 political killings during the campaign.

Security analysts say many of the deaths are at the hands of criminal organisations.

Since the war on drugs began, many of the country’s huge cartels have fragmented into smaller groups, increasingly focusing on regional patches.

It’s important to them that local politicians are in their pockets to allow them to carry out their illegal operations in impunity.

Those who refuse to collude, or are aligned with rival groups, risk death.

According to Eduardo Arcos, of security consultancy firm Control Risks, that poses a threat to governance itself in areas where gangs hold sway.

“There’s really a blurred line between local politicians and criminal groups,” Arcos told Al Jazeera.

“In many cases, they work in direct cooperation; in tandem,” he said.

“And it shows that in many parts of the country because of a lack of institution building there’s a failed state in certain municipalities and areas.”

Other murky attempts to sway the elections have also been documented. The civil society coalition Accion Ciudadana Frente a la Pobreza found in a survey that 30 million Mexicans were offered financial or other benefits in exchange for their vote.

In the week before the vote, two men were arrested while carrying in their car a suitcase full of the equivalent in pesos of one million dollars. They said they were headed to the headquarters of the ruling PRI party.

Mexican elections have long been marred by vote-buying or coercion. It has yet to be seen how far the practice will affect the results this time around – especially with a youthful electorate seemingly tired of the dirty politics of the past.

Youth Vote

Nearly half of the electorate is under 40 years old. Pollsters say the youth has little faith in the government and believe it is riddled with corruption. They’re overwhelmingly urban, online and more educated than their parents and they could swing it for the winner.

That’s if they turn out.

But youth leadership of protest movements and the rescue efforts after last year’s earthquake has raised hopes that they will buck the global trend of youthful voting apathy and get involved.

Polls show that if they do, many are likely to vote in favour of Lopez Obrador.

It’s another boost for a candidate already far ahead of his rivals.

If he does win on Sunday, all eyes will also turn to the Mexican Chamber and Senate, where a majority – if his coalition with an ultra conservative evangelical party holds after the election – would give him more power to push through his plans.