BOGOTA, Colombia—Right-wing populist candidate Abelardo de la Espriella has narrowly won Colombia’s presidential election based on the preliminary “quick count” released by electoral authorities.

With over 99% of the vote counted in the preliminary tally, de la Espriella leads with 49.7% over his left-wing opponent Iván Cepeda, who has secured 48.7%. The remaining ballots were blank votes.

The razor-thin margin means no final result has been certified, and a slower, official manual count is expected over the coming days. Historically, Colombia’s quick counts have closely tracked final certified results.

Reacting to the result, De la Espriella posted on social media: “Today begins a new stage for our country, a stage built on the free and democratic will of millions of citizens who chose to believe in a great, safe, and prosperous Colombia full of opportunities.”

In a speech on Sunday evening, Cepeda, a close ally of outgoing President Gustavo Petro, said that while he recognizes the quick count result, his campaign is challenging results from around 33,000 ballot boxes.

In a series of posts on social media, Petro alleged irregularities in the preliminary vote count, and called for calm, declaring that neither candidate could “be proclaimed” until the initial count vote count was ratified.

Security was voters’ top concern in the election according to pollsters. Colombia’s armed conflict, which has lasted for decades, has intensified in recent years as armed groups and cartels expand their control over drug trafficking routes and illegal mining operations. Membership in groups has reportedly doubled over the past five years, contributing to widespread displacement and insecurity.

De la Espriella, is a millionaire businessman and criminal defense attorney who has nicknamed himself “El Tigre” (the Tiger). A political newcomer endorsed by President Donald Trump, he has pledged to pursue a tougher, more hardline approach to security.

On his first day in office he has promised a sweeping military offensive against guerrilla groups in his first day in office, stating in a recent television interview that he would “bomb all of the camps holding narco-terrorists.”