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, IBOPE said, while center-right Neves gained one percentage point to 23 percent since the previous poll in July.
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 if it were held today 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 that gap to 6 points from 8 in July.
A flagging economy and high cost of living have hurt Rousseff's popularity and fuelled a widespread desire for change among Brazilians, making this the toughest election for the ruling Workers' Party since it won office in 2002.
More than one third of Brazilian voters (36 percent) say they will never vote for Rousseff, a rejection figure that is more than double that for Neves (15 percent), according to IBOPE.
Still, the poll found that 55 percent of those surveyed believe that Rousseff will prevail and win a second-term.
Rousseff is campaigning on the social improvement delivered by her party that reduced poverty and lifted millions of Brazilians into a modern consumer society over the last decade.
Neves is running on a more business-friendly platform, vowing to restore investor confidence and solid growth to Latin America's largest economy.
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)