BRASILIA (Reuters) - Brazilian President Dilma Rousseff would win re-election in a likely second-round run-off in October, but main challenger Aecio Neves has narrowed her lead, a new poll by the IBOPE polling institute showed on Thursday.
Voter support for leftist Rousseff ahead of the Oct. 5 election was unchanged at 38 percent, while center-right Neves gained one point to 23 percent since the previous poll in July, IBOPE said.
Third-placed candidate Eduardo Campos also advanced one point to 9 percent.
The poll showed that Rousseff does not have enough votes to win the election outright and would have to face a run-off three weeks later against Neves.
In a second-round runoff vote, Rousseff would likely defeat Neves with 42 percent of the vote compared with his 36 percent, the survey found. Neves has reduced the gap to 6 points from 8 in July.
The IBOPE poll, broadcast on TV Globo, surveyed 2,506 people from Aug. 3-6 and has a margin of error of 2 percentage points.
(Reporting by Anthony Boadle; Editing by Ken Wills)