Mexicans lined up to vote for a new president on Sunday, with many hoping for a shake-up of the status quo by choosing an anti-establishment leftist whose pledge to clean up politics has resonated widely after years of violence and corruption.

Opinion polls before the election showed a double-digit lead for Andres Manuel Lopez Obrador, a former Mexico City mayor expected to inject a dose of nationalism into government and sharpen divisions with US President Donald Trump if he wins.

Lopez Obrador, 64, would be the first leftist president in decades in Mexico, Latin America's No. 2 economy, if he ousts the ruling centrist Institutional Revolutionary Party (PRI). His administration would also offer a political realignment after years of rule by centrist technocrats.

Runner-up in the 2006 and 2012 elections, he pitched himself as the only man capable of restoring faith in democracy after disenchantment grew after years of patchy economic growth and soaring levels of drug-related violence.

Long lines formed outside schools and community centers, where voters complained that previous governments have failed, particularly the administration of outgoing President Enrique Pena Nieto of PRI, who has struggled to contain crime and corruption.

Even if they were not sure about Lopez Obrador, many said he was better than his rivals, and offered a fresh start.

"In truth, I don't think any of them are worth much, but it's better (to pick Lopez Obrador), who is a useful vote against the PRI," said 22-year-old student Eugenia Gonzalez, as she waited to vote in the Mexico City suburb of Nezahualcoyotl.

"I think this has been the worst administration in many years, and far from improving things, the security situation, corruption, they're worse than ever," she added.

Mexico suffered its most violent year in recent history in 2017, and murders are still rising. A fragmented criminal landscape has prompted drug cartels to expand into fuel theft and extortion.

Since the campaign began heating up last year, at least 145 politicians and activists have been murdered. Most of them have been blamed on gangs trying to influence elections.

Just before casting his vote, Lopez Obrador, or AMLO as he is known, called for a national reconciliation after the election to end the bloodshed.

"With all my heart, I want today's election to take place without violence," Lopez Obrador said, smiling and flashing a victory sign at the polling station south of Mexico City where he arrived 40 minutes before it opened.

Seeking support from economic nationalists, leftist liberals and social conservatives, Lopez Obrador has been vague on policy details. But he vows to reduce inequality, improve pay and welfare spending as well as run a tight budget.

The law bars Pena Nieto from seeking re-election. His popularity crumbled as his name became tainted by investigations into alleged conflicts-of-interest and embezzlement scandals engulfing top PRI officials.

Lopez Obrador has spent 13 years campaigning around Mexico but has been a divisive figure since bringing much of the capital to a standstill for weeks with demonstrations to protest his 2006 election loss. His criticism of the government's economic agenda has been tempered by business-friendly aides.

He has played with the idea of referendums to resolve divisive issues like whether to continue with Pena Nieto's opening of the oil and gas industry to private capital.

Photo: AFP

Rivals Ricardo Anaya, an ex-leader of the conservative National Action Party (PAN) heading a right-left alliance, and PRI candidate Jose Antonio Meade, a former finance minister, both broadly support the energy reform. They represent the only two parties that have ruled modern Mexico.

Their efforts to catch Lopez Obrador have been hampered by attacks on each other, and some opinion polls put his lead in excess of 20 percentage points.

Careful of Trump

The next president will inherit a simmering dispute with Trump over migration and trade, with talks to rework the North American Free Trade Agreement (NAFTA) unresolved, pressuring Mexico's peso currency.

Trump has threatened to pitch North America into a costly trade war over NAFTA, and his insistence that Mexico pay for his desired border wall has deeply angered many Mexicans.

Lopez Obrador has moved carefully and wants to broker a deal with Trump under which Mexico would work to rein in illegal immigration in return for economic support.

If that proves impossible and Trump keeps provoking Mexico, few think the fiercely patriotic Lopez Obrador will stay silent.

How much heft he can bring to bear domestically and internationally will depend on his control of Congress, where no party has held an outright majority since 1997.

Polls suggest his National Regeneration Movement (MORENA), a party that has only existed formally since 2014, could be close to a majority. Markets may react negatively if voters give him too free a hand in Congress.