Voters head to the polls amid concerns about corruption, peace and the Venezuela crisis.

Colombians are voting in the country’s first presidential election since a controversial peace deal between the government and FARC rebels in 2016.

Polls opened at 13:00 GMT in a campaign that has been dominated by a battle between two candidates: Ivan Duque of the right-wing Democratic Centre party and Gustavo Petro, a leftist candidate who is a one-time rebel and former mayor of Bogota.

Polls are set to close at 21:00 GMT. Results are expected around 01:00 GMT.

The vote is expected to reflect the social polarisation that the landmark agreement created.

Despite the challenges of peace and managing the fallout from the Venezuelan crisis, voters are more concerned about corruption, healthcare and unemployment, according to Invamer polls.

Colombia’s election comes as several Latin American countries choose new leaders over the next few months, including such regional power players as Brazil and Mexico.

With six more presidential elections following in 2019, Colombia‘s neighbours will be awaiting Sunday’s results with interest.

How will the vote work?

To win the presidency, a candidate must secure a majority of votes. Failing that, a second round will be held on June 17. The winner will begin a four-year term in August.

The vote follows congressional elections on March 11, which are often seen as bellwethers for the presidential elections. The candidate whose party wins most seats in the congressional elections often goes on to become president.

Right-wing and left-wing coalitions also held primaries on March 11, in which Ivan Duque and Gustavo Petro emerged as the candidates for each group respectively.

Around 36 million Colombians are eligible to vote, according to a March 2018 electoral census. Voter turnout has traditionally been low, with 48 percent voting in the second round of the last presidential election in 2014.

The May 27 vote will be the first presidential election since the peace deal with the FARC, although the party is not fielding a candidate [Ivan Valencia/AP]

What are the key issues?

Corruption: Colombia has been rocked by major corruption scandals in recent years, pushing the issue to the top of the political agenda.

Politicians from both sides have been tainted by alleged associations with Odebrecht, a Brazilian construction company that paid bribes to officials across Latin America.

Allegations of vote-buying have cast a shadow over previous elections, including in March where several polling stations ran out of ballots before polls closed during a congressional election.

Employment: According to Invamer polls, voters think unemployment is the most important issue Colombia’s next president should address.

Unemployment rose sharply to 11.8 percent in January 2018. The unemployment rate in cities is rising as workers move from rural areas seeking opportunities.

Candidates from both the right and left-wing coalitions have promised job creation and pension reform.

Healthcare: Colombia’s complex and overpopulated healthcare sector is a main concern for voters, according to Invamer opinion polls.

The country has a mixed-market system, with one public health insurance provider and various private options. Successive governments have attempted to simplify the existing system and expand free healthcare.

Who are the main candidates?

Incumbent President Juan Manuel Santos is ineligible to run for re-election, having served the maximum two terms.

Duque’s, left, close relationship with Uribe, right, has boosted support for his candidacy [Nacho Doce/ Reuters]

Ivan Duque: Currently the man to beat, the right-wing Centro Democratico (Democratic Centre) politician has been leading opinion polls since January.

A lawyer and senator, Duque is the protege of former President Alvaro Uribe, who led the country from 2002 to 2010. Uribe remains a highly influential figure in Colombian politics, with as many as one in five Colombians telling pollsters they would vote for the candidate backed by Uribe.

Duque has vowed to close the poverty gap, simplify the country’s tax code and pursue the complete eradication of coca in line with his tough stance on drugs.

If elected, he wants to pass constitutional reforms to undo key aspects of the peace deal, including those that allow the FARC to participate in politics.

Critics say Duque lacks experience, having only entered politics in 2014, and fear he is too closely tied to both Uribe and big business.

Petro has promised to tackle corruption by fully separating Colombia’s political and judicial systems [Christian Escobar Mora/Reuters]

Gustavo Petro: The left’s candidate is a former mayor of Colombia’s capital, Bogota, and a one-time member of the M-19 armed group.

Petro has promised to fully separate the country’s political and judicial systems, in a bid to strengthen democracy and tackle corruption.

Inequality is high on Petro’s agenda: he wants to improve working conditions, nationalise healthcare and introduce land reforms to benefit the country’s rural poor.

He supports peace with the FARC, but has criticised the deal, saying it ended the war without resolving its effects on society.

Petro’s critics say his plans to shift Colombia’s economy from oil to agriculture are unrealistic, but his supporters see him as the most credible challenger of the traditional power bases.

Other candidates include a former mayor of Medellin, Sergio Fajardo; former vice president under Santos, German Vargas Lleras; and Humberto de la Calle, an elder statesman of Colombian politics, as well as a number of lesser-known figures.

What role will the peace deal play?

Santos, left, and FARC leader Rodrigo Londono, right, signed the peace deal in Havana, Cuba, after four years of negotiations [Ramon Espinosa/AP]

In a referendum on October 2, 2016, Colombians narrowly rejected a deal to end the armed conflict between the Colombian government and the Revolutionary Armed Forces of Colombia (FARC). A revised deal was signed the following month without a public vote.

Santos was awarded the Nobel Peace Prize for his efforts in bringing the decades-long conflict – which had killed 220,000 people and displaced nearly seven million – to an end.

Many Colombians, however, felt the agreement was too lenient on FARC by allowing its members to enter politics and avoid imprisonment for crimes committed during the conflict.

The agreement permitted FARC to rebrand itself as a political party – the Common Alternative Revolutionary Force – and guaranteed it five seats in each of the country’s two chambers of parliament, regardless of vote share. {articleGUID}

This condition angered Colombia’s other political parties, none of which have guaranteed representation.

FARC will not field a candidate in Sunday’s elections after their presidential hopeful, Rodrigo Londono – better known by his nom de guerre Timoleon Jimenez or nickname Timochenko – pulled out of the race due to health problems.

The idea of the former rebels as politicians is still divisive among voters. In March’s congressional elections, FARC secured just 0.5 percent of the vote and at some campaign events, candidates were pelted by stones and tomatoes.

The result of Sunday’s vote will throw the future of the deal into uncertainty, with both leading candidates openly critical of aspects of the agreement.

How will the Venezuela crisis affect the election?

Almost one million Venezuelans have crossed the porous border with Colombia [Jaime Saldarriaga/Reuters]