The run-off is needed because Santos fell just shy of a tally of more than 50% that would have given him outright victory.
The main rival to Santos is the Green Party’s Antanas Mockus, a philosopher-mathematician and former mayor of Bogota, who took 21.5% of the vote.
After his comfortable win and surge in support, Santos is favourite to win the presidential race, said analysts, while Mockus is likely to struggle to secure much needed new votes.
Santos,
