Voters in Colombia began to cast their votes for a new president on Sunday in an election that may give the South American country the first left-wing leader in its history.

The leftist candidate, Gustavo Petro, has captured international attention due to his dominant lead in pre-election polls, in what is considered to be a traditionally conservative country.

The 62-year-old ex-guerrilla and former mayor of the capital, Bogota, is hoping to win over 50% of the votes in Sunday's first-round and thus avoid a second-round run-off against his main right-wing rival.

His running mate, Francia Marquez, is hoping to become the country's first-ever black female vice president.

Federico Gutierrez, the former mayor of Medellin, is standing as the candidate for an alliance of right-wing parties and has been polling at around 25% in comparison to Petro's 40%. He has also received support from outgoing President Ivan Duque, although it is yet to be seen whether support from the leader with record-low approval ratings will prove advantageous.

Polls will be open between 8 a.m. and 4 p.m. local time (1300 to 2100 GMT) with just under 39 million people eligible to take part. The second round, if needed, is set for June 19.

What do the candidates stand for?

Gutierrez has tried to distance himself from claims that he is the successor to Duque and the conservative "uribismo" movement he's associated with — named after former President Alvaro Uribe Velez who ran the country between 2002 and 2010. 

The 47-year-old center-right candidate has made pledges for government spending including a basic income for some 5 million households. Colombia has one of the highest levels of income inequality in the world and about 40% of the population lives in poverty, according to the World Bank.

Petro, who lost against Duque in 2018, has plans to redistribute pensions, make public universities free, and tackle the country's inequality and poverty. He has also said he will put a stop to new oil and gas projects.

The third-highest polling candidate, the independent Bucaramanga Rodolfo Hernandez, is running on a platform of anti-corruption promises. The 77-year-old is also under investigation over whether he intervened to benefit a company that his son has been linked to.

Colombia's violent past and present

Petro's popularity has been met with pushback from parts of the country that maintain a deep-rooted fear of the left which is associated with both the guerrilla groups that kept up a decades-long conflict with the central government, as well as the disastrous economic policies of neighboring Venezuela.

However, it was under Duque's presidency that peace talks with the last remaining guerrilla group, the ELN, were suspended following the historic agreement with the FARC just prior to Duque's election. Petro, a former member of the M-19 urban rebel group that laid down its arms in 1990, has vowed to restart peace talks.

Colombia's history has been marked by decades of civil war, violent drug traffickers, guerrilla groups, and political assassinations — both Petro and Gutierrez have received death threats. The Duque government was also internationally condemned last year after its violent crackdown on anti-poverty protests saw dozens of civilians killed.

Candidates have expressed concerns over voting irregularities during legislative elections in March, however, officials have put these down to clerical errors and said that there is no chance of electoral fraud.

Observers from the Organization of American States and the EU will be present and some 300,000 armed police and soldiers have been deployed to protect the 12,000 polling stations.

ab/jcg (EFE, Reuters, AFP)