Opposition candidate Aecio Neves is running neck-and-neck with leftist incumbent Dilma Rousseff on the eve of a runoff vote that will decide Brazil’s presidential election, a poll published yesterday said.

Brazilians vote today in the closest election in decades between a pro-business senator who is promising to revive a stagnant economy and a Workers’ Party president who vows to protect social programmes that have lifted millions from poverty.

Neves has 45.3% voter support against 44.7% for president Rousseff, the survey by the smaller MDA research company said. Brazil’s more closely watched polling firms are giving Rousseff a 6- to 8-percentage point lead.

Excluding undecided voters, spoiled and blank survey responses, Neves has 50.3% of the valid votes against 49.7% for Rousseff, the MDA showed. The gap between them is well within the poll’s margin of error of plus or minus 2.2 percentage points and is considered a statistical tie.

The MDA poll commissioned by the transport industry lobby CNT surveyed 2,002 people between Thursday and Friday.

Brazil’s top polling firms Datafolha and Ibope will release their final polls on Saturday night on the newscast of Brazil’s TV Globo network just hours before voting stations open.

Rousseff, 66, a former guerrilla who was jailed and tortured for fighting Brazil’s 1964-1985 dictatorship, spent yesterday morning in her southern stronghold of Porto Alegre, where she was holding a march.

Neves, the business-world favorite, was meanwhile in his native state of Minas Gerais in the southeast to pay a visit to the grave of his grandfather Tancredo, a leading figure in the democratic transition who was elected president in 1985 but died before taking office.

The 54-year-old senator was later due to visit a Catholic church in the town of Sao Joao del Rei and give a press conference.

Rousseff, who was elected Brazil’s first woman president in 2010, taking the reins from her popular Workers’ Party (PT) mentor, Luiz Inacio Lula da Silva, has had to fight tooth and nail to re-emerge as the front-runner.

In the build-up to the October 5 first-round vote, she had to fend off environmentalist Marina Silva, who took the polls by storm vowing to become the south American country’s first “poor, black” president when she dramatically entered the race after her running mate Eduardo Campos died in a plane crash.

No sooner had the PT’s electoral machine dispatched Silva -- who exited the first round with 21% of the vote, to Rousseff’s 42% and Neves’s 34% -- than the incumbent had to beat back Neves, who converted the momentum of his first-round comeback into a narrow lead.

With the candidates fighting for every vote in this sprawling country of 202mn people where voting is compulsory, the campaign took on a level of virulence not seen since the return to democracy.

Rousseff, who is known for her toughness, accused Neves of nepotism when he was governor of Minas Gerais, played up a media report that he once hit his then-girlfriend in public and suggested he was driving “drunk or on drugs” when he refused to take a breathalyser during a 2011 traffic stop.

Neves fought back, accusing Rousseff of incompetently running the recession-hit economy and of “collusion” in a multi-billion-dollar kickback scandal at state oil giant Petrobras.

That charge returned to the fore on the eve of their final debate Friday when conservative news magazine Veja reported that Rousseff and Lula “knew everything” about the alleged embezzlement scheme, citing a shady money dealer accused in the case.

Neves opened the debate asking Rousseff about the report, which he called the culmination of “the most sordid campaign in history.”

“Veja has presented no proof,” Rousseff fired back, condemning the article as “slander and defamation” and repeating her vow to sue.

“The people aren’t stupid. The people know this information is being manipulated,” she said.

“I’m certain that they’re going to show their indignation on Sunday.”

When Neves zeroed in on the congressional vote-buying scandal that brought down key members of Lula’s administration, Rousseff fired back by bringing up a similar scandal from the 1990s that rocked his Social Democracy Party (PSDB) in Minas Gerais, where Neves was later governor.

“There was a trial over the ‘big monthly allowance’ scandal linked to my party. They were convicted and went to jail,” she said.

“But in the ‘big monthly allowance’ scandal in your party, no one was ever convicted or punished... You’re the first to talk about corruption, but I can list all the times you guys weren’t judged and walked free,” she added, rattling off a list of past scandals.

She then went for the jugular, adding that one of the best-known of the Minas Gerais group “is the coordinator of your campaign” in the state.

Neves, the 54-year-old scion of a famous political family, retorted: “The best measure against corruption would be to take the PT out of power.”

After the magazine’s report, a small group of protesters invaded the publisher’s headquarters, spray-painting “Veja lies” on the building and strewing trash at its gates, media reports said.

Brazil is divided along social lines heading into the election.

The poor, particularly in the impoverished northeast, are loyal to the PT thanks to landmark social programmes that benefit 50mn people and have helped lift 40mn from poverty in the past 12 years.

The country’s elites are meanwhile exasperated with interventionist economic policies such as petrol price controls and high taxes.

The battle is for the middle class in the industrialised southeast, the cradle of million-strong protests against corruption and poor public services that shook the country last year.

This demographic is torn between voters loyal to Lula for presiding over nearly a decade of prosperity and social gains from 2003 to 2011, and those frustrated with Rousseff’s government.