Last polls suggest Brazilian President Dilma Rousseff is expected to win by about 8 percent in the second round of elections for head of state held Sunday.

Rousseff is now facing A?cio Neves, the candidate of the Brazilian Social Democracy Party (PDSB) in what many experts say has been the tightest race since democracy was restored in Brazil in 1985.

Different surveys cited by the BBC suggest support for the incumbent would be at about 52-53 percent, but other pollsters say figures can easily change due to the 10-percent share of voters who are either undecided or are intending to cast a blank vote.

She received about 41% in the first round, while Neves was second with slightly over 33 percent.

Critics accuse the President of failing to keep the Brazilian economy afloat, with GDP stagnating after years of staggering success that placed the country among the world's leading economies.  

But advocates remind of her social welfare programs and efforts to eradicate poverty which have generally yielded results.

A bribery scandal at the state-owned oil giant Petrobras marred her campaign, with Neves accusing the cabinet of being corrupt.

Rousseff's Workers Party (PT) has been in power since 2002 after her predecessor Luiz In?cio Lula da Silva, credited with helping Brazil's economy on its feet, assumed office.

Neves, on the other hand, is often described as more business-friendly, but has vowed not to suspend social welfare programs.

He surprisingly came second in October 5's first round after environmentalist Marina Silva had been tipped for weeks to be Rousseff's most dangerous rival.

About 142 million Brazilians are eligible to vote on Sunday.