With 98.22 percent of the ballots counted at the time of press, De la Espriella secured 49.77 percent of the votes, while his rival Ivan Cepeda garnered 48.59 percent, according to preliminary results released by the National Civil Registry, Xinhua reported.
The second round of voting took place from 8 a.m. local time (1300 GMT) to 4 p.m. (2100 GMT) on Sunday, with more than 41.4 million registered voters eligible to cast ballots at approximately 13,000 polling stations nationwide.
According to Colombia's current electoral system, a candidate must win over 50 percent of the votes in the first round to be elected president directly. If no candidate reaches the threshold, the top two candidates advance to a runoff, where the candidate with the most votes wins.
De la Espriella, 47, is a lawyer. As a non-traditional political figure, he advocates for shaping national governance through an iron-fisted approach to security and drastic cuts in public spending. His running mate is Jose Manuel Restrepo, Colombia's former Minister of Finance and Public Credit.
The new president will take office on Aug. 7.