Like Zapata, Cristian Madrigal, 20, an economics student in Medellín, does not trust Duque's proposals to amend the process.

“Duque’s proposals to change the peace agreement are being influenced by Álvaro Uribe, who clearly has a hatred towards the Farc," he said. "The deal isn’t perfect, but at least with the capture of Santrich, we know there is no impunity for the Farc.”

Duque has denied he wants to scrap the deal completely.

Rather, his campaign has sought to appease a broad section of Colombian society troubled by an agreement that could see ex-combatants escaping lengthy jail sentences.

As part of the transitional justice system, former guerrillas as well as members of the armed forces who own up to war crimes face five to eight years of “alternative sanctions”, which could include house arrest or community work.

A bill that guarantees the FARC, now a political party, five seats in each of the upper and lower houses of Congress through 2026 is also fueling opposition to peace.

“There is a complete imbalance,” Sebastián Velásquez, executive director of the Colombian Federation for Victims of the FARC (Fevcol), told NBC News. “Political participation is something that should come after prison sentences have been served.”

María Cecilia Robledo, 41, an engineer based in Medellín, agrees with this view. “I don’t really support any of the candidates, however I agree with Duque that those guilty of atrocities should pay for their crimes.”

Last month’s arrest of former FARC commander Jesús Santrich for allegedly conspiring to export tens tons of cocaine to the United States simply validated the widely held belief that the guerrillas cannot be trusted.

Patience is also wearing thin amid the sluggish pace of the peace process.

In a recent report, Notre Dame University’s Kroc Institute, which is monitoring the enforcement of the deal, said that just 17 percent of the 558 stipulations in the agreement had been fully implemented.

While the Institute praised demobilization, a lack of progress on tackling rural inequity, considered to be the root of the conflict, was “worrisome”, the report said.