Bogota, Colombia – Colombians are heading to the polls to choose their first new president since the landmark 2016 peace deal that brought an end to more than 50 years of conflict.

Ivan Duque, of the conservative Democratic Center party, won May’s first round with nearly 40 percent of the vote. He faces leftist Gustavo Petro, the former mayor of Bogota and one-time rebel with the now defunct M-19. Petro received 25 percent of the vote in the first round.

The election has been touted by some as a referendum on the 2016 peace deal with the Revolutionary Armed Forces of Colombia (FARC), with Duque wanting an overhaul and Petro supporting the fragile peace process.

The latest opinion polls showed Duque in the lead by as many as 15 points.

Polls opened at 13:00 GMT on Sunday and closed at 21:00 GMT, with results expected a few hours later.

The candidates’ distinct political visions will mark a departure from the current trajectory of the Andean country as it moves into the post-peace accord era and will dictate how Colombia responds to a peace agreement under strain, a concerning boom in coca production and a struggling economy.

Peace process

Duque has campaigned on a promise to roll back parts of the 2016 peace agreement that was signed by outgoing President Juan Manuel Santos and the FARC, formally ending 52 years of conflict that left at least 220,000 people dead and more than seven million displaced.

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Sunday’s elections will decide “if Colombia returns to violence or it will build a new era of peace”, said Petro, a defendant of the peace agreement whose supporters fear rival candidate Duque will jeopardise the peace process.

Duque is supported by former-president, Alvaro Uribe, one of the peace accord’s fiercest critics for its perceived soft judicial treatment of “FARC terrorists”. Duque says his party “does not want to tear the agreement to shreds” but rather “make it clear that a Colombia at peace is a Colombia where peace meets justice”.

Observers and some voters fear, however, that Duque could imperil the peace accord’s implementation as a number of its provisions must still be finalised.

“A vote for Duque is a vote for Uribe: a return to war with the guerrillas and the death of thousands more young people”, said Elizabet, a local business manager who wished not to use her surname. “That is not the country I want,” she added.

Duque has proposed a tougher stance on FARC leaders who are involved in drug trafficking, and revoking the 10 congressional seats guaranteed for the FARC by the deal until they have been tried.

Jorge Restrepo, director of the Conflict Analysis Research Centre (CERAC) in Bogota, told Al Jazeera that revoking the FARC’s guaranteed congressional seats is “a threat for a fundamental element of the agreement which is political participation for ex-combatants”.

According to Restrepo, although Duque “may not be able” to pull off major changes, “it is a matter of guarantees for the FARC … and he is a candidate that offers less guarantees.”

Analysts like Restrepo fear that threatening the FARC will push more former rebels to abandon the peace process and join dissident groups that refuse to disarm. It could also endanger the latest on-off peace process with Colombia’s second-largest rebel group, the ELN – should Duque wish for it to continue.

Another concern is that Duque could marginalise the peace process altogether.

“Duque is not going to do something so stupid to the peace accord that it convinces a large percentage of FARC members to re-arm”, says Adam Isacson, an expert on Colombian security at the Washington Office on Latin America. “Instead, Duque would submit the accords to death by a thousand cuts, doing the absolute bare minimum to implement the reforms that the Santos government agreed to in Havana.”

War on drugs

The two candidates also offer radically different approaches to tackling Colombia’s boom in coca production, which according to the UN surged from 96,000 hectares to 146,000 in 2016.

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Duque says he will return to the controversial practice of fumigation, while Petro has strongly criticised the failings of “the war on drugs” and would put more emphasis on substitution and targeting its root causes.

“The election result is likely to be a sharp fork in the road for Colombia’s drug policy”, Isacson told Al Jazeera.

“Duque would go back to the past, using harshly punitive strategies that don’t address underlying causes but, for a while at least, keep production and trafficking at ‘manageable’ levels,” he said. “Petro says he wants to get off that ‘stationary bicycle’ and go after the reasons that farmers grow coca and the drug trade thrives in Colombia.”

Economy

Having to foot the bill for the peace process just after the price of oil crashed in 2014 means Colombia’s economy has faced a rough ride in recent years. But it does finally appear to be showing some positive signs of growth.

Internationally, investors and rating agencies are content with Colombia’s “debt payment, international commitment, remained in balance”, Sergio Guzman, Principal Colombia Analyst at Control Risks, told Al Jazeera.

“Duque would definitely maintain the country’s economic trajectory as it has been,” Guzman added.

Petro, however, plans to move Colombia’s export model away from oil, gas and mining, and towards the more environmentally friendly and sustainable industries of agriculture and services.

This plan is not only “aggressive”, but “very vague” and “unrealistic”, Guzman said, “as oil and extractive exports represent over 50 percent of Colombia’s exports and 26 percent of government revenue.”

“Petro would make markets very fearful for the future of Colombia”, the analyst says.

The leftist candidate also plans to address the country’s inequality by buying out land from big agro-industrial companies and redistributing it to poorer families.

But not everyone is convinced by such policies.

“I don’t want a guerrilla running the country,” Yeimi, a barista and mother of three, told Al Jazeera.

“I see desperate Venezuelans in this cafe every day because [Hugo] Chavez started giving everything away for free – like Petro wants to,” she said, referring to the one million Venezuelans who have fled to Colombia over the 15 months.

“That’s not what I want for my children,” she added.

The Venezuela crisis is one of several other prominent issues, including rampant political corruption, that the selected candidate will have to wrangle with in a highly divided nation.

“Any president is going to have a hard time governing, it’s not going to be easy for anybody,” Guzman concluded.