BOGOTA (Reuters) - Colombian President Juan Manuel Santos would win more support than any other candidate in the first round vote for president, but the share of the electorate who will not pick any candidate on the ballot remains the biggest block of voters.
A poll by Ipsos Napoleon Franco showed that Santos would garner 25 percent of the vote against rival candidates on May 25, while those who would mark the ballot in support of no candidate would be 27 percent. Another 23 percent are undecided, the survey, published on Monday on RCN Radio's website, said.
The number of voters who have opted not to vote for any individual candidate is higher than usual and is considered a protest vote but is likely to fall as the election nears, according to Ipsos.
A candidate must win more than 50 percent to avoid a runoff on June 15.
Centre-right Santos is seeking re-election for a second straight term in office.
The poll showed right-wing opposition candidate Oscar Ivan Zuluaga, would get 8 percent support if the election was held now.
Zuluaga, candidate for former President Alvaro Uribe's party, is campaigning strongly against the peace talks with the Marxist FARC, or Revolutionary Armed Forces of Colombia, which Santos launched at the end of 2012 in Cuba.
Santos had 46 percent favourability rating in the poll conducted on January 28 and 29.
In November, he had 44 percent approval. Another 47 percent had an unfavourable image of the president.
Ipsos interviewed 1,008 Colombians in eight cities nationwide and the poll had a margin of error of 3.1 percent.
(Reporting by Helen Murphy Editing by W Simon)