The far-right lawyer Abelardo de la Espriella won the first round of Colombia’s presidential election on Sunday and will face senator Iván Cepeda, the candidate backed by leftwing president Gustavo Petro, in the runoff.

With 99.9% of ballots counted, the outsider and Donald Trump admirer Espriella secured 43.7% of the vote – just over 10.3m votes – compared with 40.9% (about 9.6m votes) for Cepeda, a philosopher and human rights activist who has served as a senator since 2014.

The two will face each other in a runoff on 21 June.

Although polls in recent weeks had already detected Espriella’s rapid rise, most still showed him trailing Cepeda, who for months seemed to hold a solid lead.

Espriella appears to have consolidated much of the vote that had previously been going to the rightwing senator Paloma Valencia, who at one point polled above 20% and was running in second place but finished Sunday with just 6.9%.

Espriella, who calls himself el Tigre (the Tiger), celebrated the result: “Compatriots, defenders of the homeland, more than 10 million Colombians placed their trust in el Tigre and joined the pack … In 21 days, we are going to change the history of Colombia forever,” he said in a video alongside his wife and children, all wearing shirts of the Colombian national football team.

After a wave of victories by far-right candidates in recent years in Argentina, Chile, Ecuador, Bolivia and Honduras, Colombia remains one of the few countries in Latin America still governed by the left, alongside Mexico and Brazil, which will hold its own presidential election in October.

Espriella is an outspoken admirer of several rightwing leaders in the region, including the US president, Donald Trump, El Salvador’s Nayib Bukele and Argentina’s Javier Milei.

A criminal lawyer and millionaire businessman who has never held public office, Espriella built his campaign around a promise to return to a policy of total confrontation in response to Colombia’s worsening security crisis, now considered the worst since the landmark 2016 peace agreement between the government and most of the Revolutionary Armed Forces of Colombia (Farc).

Espriella advocates ending Petro’s “total peace” policy of negotiating the dismantling of criminal groups – of which Cepeda is widely regarded as the architect – and replacing it with a mano dura (iron-fist) strategy inspired above all by El Salvador’s populist strongman Bukele, who has imprisoned at least 2% of his country’s adult population as part of a controversial crackdown on gangs. Even the lawyer’s neatly trimmed beard and habitual use of baseball caps have drawn comparisons with Bukele’s style.

Espriella has incorporated the animal into much of his campaign branding. He has attracted controversy by attacking journalists and, at one point, telling a radio host that he was winning over female voters because of the size of his genitals.

He first became nationally known through years of legal work for figures such as the Colombian businessman Álex Saab, who was widely regarded as the principal financial frontman for Nicolás Maduro’s regime in Venezuela and was recently deported to the US by the acting president, Delcy Rodríguez.

In a speech on Sunday night, Valencia acknowledged the result and endorsed Espriella in the runoff.

On the eve of the vote, Espriella had already dominated headlines after holding a video call on Friday evening with Ecuador’s far-right president, Daniel Noboa, whose relations with Petro had been severed for months.

The conversation resembled a meeting between two heads of state, during which they discussed issues such as border security and the extradition of criminals. Espriella asked Noboa to lift the additional 75% tariff Ecuador had imposed on Colombian imports; the president agreed and said the measure would take effect on Monday, immediately after the vote.

Colombia’s foreign ministry issued a statement describing Noboa’s gesture as a “deliberate interference in the electoral process”, adding: “This intrusion by a foreign head of state into the democratic affairs of another country constitutes a flagrant violation of the principle of non-intervention in internal affairs, a threat to national sovereignty and an attack on the democratic system.”

Despite widespread concern about security, election day itself passed peacefully.

The past few months have been marked by a surge in guerrilla attacks, homicides, kidnappings, forced displacement and massacres, and last year the rightwing senator and presidential hopeful Miguel Uribe Turbay was shot during a campaign event by a Farc dissident group and later died.