MercoPress. South Atlantic News Agency

Brazil's Dilma slightly ahead show two opinion polls released on Monday

The Datafolha poll showed the incumbent with 46% support, up 3 percentage points from the previous poll released on Oct. 15. Neves figures with 43%.

President Dilma Rousseff is gaining momentum but remains locked in a dead heat with challenger Aecio Neves ahead of Sunday's runoff to Brazil's presidential election, according to two surveys released on Monday.

Centrist candidate Neves lost a slight but statistically insignificant lead over Rousseff for the first time since the first round of elections on Oct. 5, according to the survey by Datafolha polling firm.

Since then, the presidential race has turned increasingly ugly as the candidates scramble for undecided voters. They have swapped accusations of corruption and economic mismanagement in heated televised debates over the past few days in what is shaping up to be Brazil's tightest election in decades.

The Datafolha poll showed the incumbent with 46% of voter support, up 3 percentage points from the previous poll released on Oct. 15. Support for market favorite Neves dropped 2 percentage points to 43%.

A survey by polling firm MDA released earlier on Monday showed Rousseff with 45.5% of voter support versus 44.5% for Neves. The difference between the two remains within the margin of error of both polls.

Excluding undecided voters, spoiled and blank survey responses, the Datafolha poll showed Rousseff had 52% against 48% for Neves, a senator and former state governor.

Brazil's currency and stock markets extended losses earlier on Monday after the MDA poll showed Neves of the Brazilian Social Democracy Party lost momentum.

Brazilian markets have been extremely volatile throughout the campaign, surging with each poll favoring Neves and slumping with surveys that show Rousseff gaining ground. After four years of sluggish growth and heavy-handed economic policies under Rousseff, investors are eager for a new government.

Behind the slide in support for Neves could be his climbing rejection rate following a flurry of negative television campaigning by the Rousseff camp. Forty percent of interviewees said they would never vote for Neves, up from 38% in the past poll, surpassing for the first time the rejection rate of Rousseff in the race, Datafolha said.

The percentage of undecided voters remained unchanged at 6%, the Datafolha poll showed, meaning the candidates have not been able to persuade those voters in the final week of the campaign. It also shows that a corruption scandal rocking state-run oil company Petrobras has so far not hurt Rousseff's popularity.

Rousseff's approval rating climbed from 40% to 42%, its highest since June of 2013, Datafolha said.

Datafolha interviewed 4,389 voters on Monday in a poll with a margin of error of 2 percentage points in either direction. The survey was commissioned by the Globo media group and the Folha de S.Paulo newspaper.

MDA interviewed 2,002 voters over the weekend in a poll commissioned by the transport lobby CNT. The poll's margin of error is 2.2 percentage points.