Leftist Colombian presidential candidate Gustavo Petro, a former guerrilla vowing to tackle grating inequality, held a big lead ahead of the May 29 vote, a poll showed late on Thursday, though center-right rival Federico Gutierrez saw an uptick in support.
Petro, who was the mayor of Bogota between 2012 and 2015, had 40.6% support, according to pollster Invamer. That is three percentage points lower than what he had in an April 22 poll.
Gutierrez, the former mayor of Colombia's second-biggest city Medellin, has 27.1% support, up from the 26.7% he got in April.
If no one wins more than 50% in the first round of voting and the two men head to a June run-off, Petro would win 52.7% against 44.2% for Gutierrez, the survey showed.
Petro has pledged to stop all new oil development and redistribute pension savings, while Gutierrez has promised better salaries and cuts to inefficient government spending.
Independent candidate Rodolfo Hernandez, also a former mayor, saw a significant leap in first-round support - jumping to 20.9% from 13.9% in April.
Hernandez, a businessman from the city of Bucaramanga who casts himself as the anti-corruption candidate, has attracted attention for his whimsical uploads to social media site TikTok.
In a run-off between Petro and Hernandez, the leftist would win 50% to 47.4% for his opponent, the poll showed.
Support for centrist Sergio Fajardo fell from 6.5% to 5.1% support.
More than 39 million Colombians are eligible to vote in the election.
The poll has a margin of error of 2.2% and comprised 2,000 surveys. It was conducted between May 13 and May 18.
(Reporting by Julia Symmes Cobb; Editing by Paul Simao)
