Colombians head to the polls today in a presidential election that may give the conservative South American country its first ever leftwing leader and first black vice-president. Frontrunner Gustavo Petro, a former M-19 guerrilla fighter and senator, faces several rivals, but his main challenger is Federico Gutiérrez, the former mayor of Medellín – Colombia’s second city – who leads a rightwing coalition with close ties to the incumbent government of President Iván Duque. Rodolfo Hernández, a business magnate and social media firebrand, has also seen a late surge in the polls. If no candidate secures more than 50% of the vote, a run-off election will take place in June. Petro’s campaign has been boosted by support from a generation of young voters politicised during an unprecedented wave of protest last year. “In Colombia we’re tired of the same thing,” said Rosa Botero, a student, at Petro’s final campaign rally in the city’s historic Plaza Bolívar last week. “Petro could change Colombia.” Petro’s opponents, meanwhile, claim that his victory could portend a nationwide collapse like that ushered in by the late Hugo Chávez, who led neighbouring Venezuela to economic and social ruin. Whoever wins the presidency will face severe challenges. The country was paralyzed by protests last year against inequality, while violence by dissident rebels and drug militias continues to plague cities and the countryside. Inflation is rising, and the country is struggling to cope with nearly 2 million migrants from neighbouring Venezuela. The historic peace deal signed with the leftist Revolutionary Armed Forces of Colombia (Farc) in 2016 is also on the ballot. That deal formally ended half a century of civil war that killed 260,000 people and displaced 7 million, but the government has been accused of slow-walking its implementation. Petro is a fervent supporter of the deal, while Gutiérrez is viewed as a sceptic. “This is a historic election because it is the first time that the left has a real chance of getting in power, and that is a result of the peace process,” said Laura Gil, a political scientist and columnist. “It is a proposal that brings together social movements that weren’t able to express themselves electorally due to the sword of Damocles that hung over them during the armed conflict.” The campaign has been marked by threats of violence against Petro and his running mate, Francia Márquez, who if elected would be one of two black female vice-presidents in Latin America, alongside Epsy Campbell Barr of Costa Rica. Both Petro and Márquez have spoken at rallies from behind bulletproof shields. The National Liberation Army (ELN), another leftist rebel group, announced a ceasefire in the run-up to Sunday’s vote, but other factions and criminal groups have routinely targeted political candidates and polling stations in recent years. Polls will close at 4pm local time, with results expected a few hours later though Petro and some of his allies have warned that the election could be susceptible to fraud, worrying observers in a country that prides itself on its relative political stability.