Left-wing candidate Andrés Manuel López Obrador is a clear favourite

A 64-year-old left-wing candidate is widely expected to win today's presidential election in Mexico.

Andrés Manuel López Obrador - often referred to as AMLO - has a clear lead in the polls and is promising to end the country's high murder rate and tackle widespread poverty.

At his final campaign event, he pledged to 'cleanse' the country, telling tens of thousands of gathered supporters there would be a "peaceful, orderly but deep transformation" of Mexico.

A victory for the populist candidate would mark a major blow to the establishment parties who have held power in the country for decades.

Three other candidates are also running for president, although polls show AMLO enjoying a 20 point lead over his nearest rival Ricardo Anaya.

Current president Enrique Peña Nieto is ineligible for re-election - although polls in recent years have shown sharp declines in his popularity.

Electoral advertising is displayed next to a highway in Mexico City. Picture by: Ramon Espinosa/AP/Press Association Images

As well as voting for a new president, Mexicans will also be voting for hundreds of national and local representatives.

While the campaign has seen huge crowds come out in support of candidates, it has also been a race marred by violence.

With many drug and criminal cartels still operating in the country, more than 130 political candidates and workers have been killed since September.