LIMA, Oct 6 (Reuters) - A jailed opponent of Newmont Mining Corp's proposed $5 billion Conga mine in Peru's Cajamarca region held a commanding lead in Sunday's regional election, a quick count by pollster Ipsos showed on Monday.
Ipsos showed Cajamarca's President Gregorio Santos heading for re-election with 45.6 percent of votes in Sunday's poll - well above the 30 percent he needed to avoid a runoff in November - after counting all ballots.
A second term for Santos would raise doubts over the Conga project getting off the ground. His closest rival, Osias Ramirez, won 18.7 percent of votes, Ipsos said
The fiery leftist leader has spent the past three months in prison after a judge ordered he be jailed until August next year pending a corruption trial.
Santos has denied wrongdoing and said his imprisonment was designed to ease the way for Newmont's gold and copper project. Peruvian law allows detained citizens to be elected to office, but not if they have been convicted and sentenced to prison.
"To be honest we expected him to win ... but not with this proportion of the vote," said Olmedo Auris, vice president of Santos' party.
"It is a clear message from the people of Cajamarca that they do not want Conga," Auris said.
Santos spearheaded protests in 2011 that forced Newmont to shelve the project.
Newmont said last year it would re-evaluate the future of the proposed mine in 2015 after Peru's nationwide local and regional elections, held on Sunday.
Peru's electoral body has not yet released any results.
Ipsos said its quick count has a 3 percent margin of error. (Reporting by Mitra Taj, Marco Aquino and Patricia Velez; Editing by Richard Lough and Dan Grebler)