Former guerrilla Gustavo Petro was set to become Colombia's first left-wing president after winning the country's presidential election run-off, according to preliminary results on Sunday.
Petro, a former mayor of capital Bogotá, received 50.49% of the votes, while conservative real estate entrepreneur Rodolfo Hernández received 47.26%, the country's electoral commission said.
"Today is a day of joy for the people," Petro tweeted after polling stations closed. "This is a victory for God and for the people and their history. Today is the day of the streets and squares."
"I called Gustavo Petro to congratulate him as the elected president of the Colombian people," incumbent president Iván Duque tweeted on Sunday. "We agreed to meet in the coming days to begin a harmonious, institutional and transparent transition."
Hernández, the former mayor of the city of Bucaramanga, conceded defeat. "The majority of citizens who voted today chose the other candidate," Hernández said in a video message. "I accept the result."
Petro's election marks the first time a leftist has been given the keys to the presidential palace in the traditionally conservative country, where left-wing politics has long had a bad reputation due to the violence of left wing militias that fed Colombia's 52-year armed conflict.
Petro has said he plans to promote peace in the country, put the brakes on the exploitation of the country's natural resources, promote tourism and increase the tax burden for big business.
Afro-Colombian human rights activist and environmentalist Francia Márquez, joins Petro as vice-president-elect.
Márquez has fought against illegal gold mining in Colombia's Cauca region, where guerilla violence was particularly bad, and received multiple death threats for her activism. In 2018, she received the prestigious Goldman Environmental Prize for her campaigning.
The challenges facing the incoming president are significant, with the economic consequences of the pandemic, social injustice and violence being just three of the most immediate.
Colombia suffered 52 years of bloody civil war between left-wing rebels, right-wing paramilitaries and state security forces. In total, some 220,000 people were killed in the conflict and millions were displaced.
In 2016, the government concluded a peace treaty with the left-wing FARC guerrillas, and while hopes were initially high for a lasting peace, violence has returned, especially in rural areas.
In addition, the incumbent conservative government has only half-heartedly implemented the peace treaty, leaving Petro the challenge of forging a lasting peace by bringing former armed groups into the country's political process.
The election of Petro marks a significant change of course for Colombia, which is the United States' most important ally in South America, particularly in its fight against drug trafficking.
As the world's largest producer of cocaine, which is mainly supplied to the US and Europe, Colombia works closely with the US to combat drug smuggling and receives several million dollars annually for its cooperation in the war on drugs.