Updated

Nearly 143 million Brazilians are going to the polls Sunday to elect president, but it's likely power will not be changing hands this time.

In a poll released Thursday, President Dilma Rousseff kept her support steady, a big comeback from just a month ago when she was trailing "green" candidate Marina Silva by 10 percentage points.

A Datafolha polling group survey said Rousseff was supported by 40 percent of those surveyed, while Silva with 24 percent and Neves with 21 percent were running neck and neck for the second spot and a place in the runoff.

A second-round vote is very likely on October 26, since no candidate appears to be getting an outright majority of votes.

In the survey, when voters were asked who they would support in a runoff vote, Rousseff led Silva and Neves by the same margin — 48 percent to 41 percent.

Datafolha interviewed 12,022 people across Brazil on Wednesday and Thursday. The margin of error was two percentage points.

In the last debate on Thursday the top presidential candidates aggressively attacked one another in the final debate ahead of this weekend's election, as new polls showed President Dilma Rousseff solidifying her lead in the race.

Rousseff was repeatedly hit with questions about big corruption cases that have dogged her Workers Party during its nearly 12 years in power — with a focus on an emerging scandal over kickbacks at the state-run oil company Petrobras, which the president says she knew nothing about.

"It's a very grave situation, what's happening with corruption. They've not taken the measures to cut it off at the root," Marina Silva, the president's top rival, said about what she called Rousseff's inaction. "The answer is always the same, 'We didn't know.' In my government we'll combat corruption first by not naming the corrupt to posts."

Rousseff shot back to both Silva and Aecio Neves, the other candidate with a chance at forcing the leader into an Oct. 26 second-round vote that she has repeatedly gone after the corrupt in government, including forcing out several of her own ministers accused of wrongdoing in the first year of her mandate.

"No government has combated corruption more than mine," Rousseff said, emphasizing her pushing federal police to investigate alleged cases. "I never swept anything under the rug. If these cases of corruption are being discovered today it's because we combated corruption."

Based on reporting by The Associated Press.

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