BOGOTA (Reuters) - Enrique Penalosa, a former mayor of Bogota, would win the presidential election in a second round against President Juan Manuel Santos, according to a poll by Centro Nacional de Consultoria published late on Monday.
The center-left Penalosa, who ran the capital city from 1998 to 2001, would finish 26 percent to 18 percent behind Santos in the first ballot on May 25, but beat him in a June runoff with 41 percent to 36 percent, the survey of 1,500 people showed.
While Penalosa, a 59-year-old economist, has been rising in recent polls, CNC conducted interviews nationwide via fixed-line telephones, a method that tends to draw answers from wealthier voters and so is not necessarily representative of voter intent as face-to-face interviews or via cellular phones.
The results differ from those of surveys by Gallup and Ipsos Napoleon Franco, which give center-right Santos a comfortable win in both rounds of voting against right-wing Oscar Ivan Zuluaga. The two pollsters tend to conduct face-to-face interviews in households nationwide.
A candidate needs more than 50 percent in the first round to avoid a runoff on June 15.
Penalosa, a contender for the Green Alliance party, is unlikely to cut off peace talks with the Revolutionary Armed Forces of Colombia, a Marxist rebel group known as FARC.
Santos has staked his legacy on ending the five-decade war which has killed more than 200,000 people, mostly civilians. He launched talks at the end of 2012.
The Green Alliance has attracted a more independent membership as well as leftist activists from the now-defunct M-19 guerrilla movement.
The poll was conducted between March 25 and 28 in 75 municipalities throughout Colombia. It has a margin of error of 2.5 percent.
Among the 33 million Colombians eligible to vote, some 14 percent said they would abstain in the second round, 5 percent said they would mark the ballot as "none of the above" and 4 percent were undecided, according to the poll.
Oscar Ivan Zuluaga, who represents the party formed by right-wing ex-president Alvaro Uribe, slipped into third place in the CNC survey of voting intent for the first round. Zuluaga is a fierce critic of talks with the FARC.
(Reporting by Helen Murphy; Editing by Jeffrey Benkoe and Marguerita Choy)