Colombian President Gustavo Petro has reiterated claims of fraud in the nation’s June election, which his party lost narrowly to conservative leader Abelardo de la Espriella.

Abelardo de la Espriella is poised to become Colombia’s next president.

Tough-on-crime outsider Abelardo de la Espriella took the lead in Colombia’s presidential race in the first round of voting Sunday night, setting up a runoff with Iván Cepeda, an ally of Colombia’s outgoing President Gustavo Petro who questioned the results of the election.

Former Colombian President Álvaro Uribe has been sentenced to 12 years of house arrest for witness tampering and bribery.