Brazilians will be voting on Sunday in a run-off election that could be one of the closest in decades, as incumbent left-wing President Dilma Rousseff tries to win a second four-year term in power against conservative opposition candidate Aecio Neves.

Most polls have shown the 66-year-old Rousseff with a 6 to 8 percent lead over Neves, though a survey by the MDA research company published on Saturday showed a gap of just over a percentage point between the two rivals, with Rousseff slightly in the lead.

In the first round of the elections at the start of October, Rousseff won 41.5 percent of votes as against 33.5 percent for Neves, but the latter can now hope for votes from the supporters of former environment minister Marina Silva, who failed to make the run-off. Silva has called on her backers to vote for Neves, 54, who is campaigning on a pro-business platform and has pledged to revive the country's stagnant economy if elected.

Rousseff, for her part, is promising a continuation of social programs that have helped alleviate poverty for millions.

The two candidates held a final television debate on Friday evening (photo above) in which they tried to win over the some 10 percent of voters who are undecided.

Corruption scandal

Rousseff's election campaign has been overshadowed by a bribery scandal at state-run oil company Petroleo Brasileiro SA, with the weekly magazine "Veja" on Friday quoting an imprisoned black market money dealer as saying that Rousseff and her predecessor Luiz Inacio Lula da Silva knew about a corruption scheme within the company.

Rousseff, who came to power in January 2011, has denied the accusations, saying in Friday's TV debate that she would take legal action against the magazine.

Voters at Sunday's run-off will also be choosing senators and governors.

tj/nm (dpa, Reuters, epd)