By Anthony Boadle
BRASILIA (Reuters) - Brazilian President Dilma Rousseff pulled ahead of opposition candidate Aecio Neves in another poll on Wednesday and looks like a slight favorite heading into what is expected to be the country's tightest election in decades.
The Datafolha poll was the fourth in three days to show Rousseff approaching Sunday's runoff vote with a slight edge over Neves, who had stirred investor enthusiasm by promising business-friendly policies to revive a sluggish economy.
Brazil's stocks and currency have sold off this week as Neves lost momentum in a race that he was recently leading. The benchmark Bovespa stock index hovered above a four-month low on Wednesday, and the real seesawed near its weakest level since 2008.
In contrast to the pessimism in financial markets, voters surveyed by Datafolha expressed a surge of optimism about Brazil's economy, suggesting Rousseff's well-oiled campaign was restoring confidence despite a recession this year.
In the new survey, Rousseff's share of voter support has risen to 47 percent from 46 percent in a Datafolha poll published on Monday. Support for Neves remained at 43 percent.
Neves dismissed recent surveys on Tuesday, noting that for the Oct. 5 first-round vote, pollsters had underestimated his support and overestimated Rousseff's by a margin of 10 points.
While Rousseff has widened her lead to 4 percentage points, the difference between them is still within Datafolha's margin of error of plus or minus 2 percentage points.
Excluding undecided voters and spoiled and blank survey responses, Rousseff has 52 percent support against 48 percent for Neves, the poll showed, the same result as on Monday.
Rousseff has gained ground by reminding voters of the rising wages and expanding social programs many have enjoyed over the past 12 years of Workers' Party rule, drawing on the charisma of her mentor and predecessor Luiz Inacio Lula da Silva.
Lula returned to the campaign trail with gusto over the past week after a brief hiatus, reinforcing his party's connection with the tens of millions of Brazilians that climbed out of poverty over the past decade.
Neves' rejection numbers have edged up in polls in recent weeks as Rousseff repeatedly said her rival would govern for the elite and cut back the vaunted social programs that have become synonymous with the Workers' Party.
Neves insists he would preserve those programs while curbing other government spending, taming inflation and ending what he calls heavy-handed industrial policies in order to restore investor confidence. But his message may be losing traction as voters' outlook brightens.
Just 15 percent of Brazilians in Datafolha's latest survey expected the economy to worsen, down from 25 percent in late September and 36 percent in early June. About a quarter worried that unemployment would increase, down from more than a third last month and half of those surveyed in June.
As a result, Neves' criticism of Rousseff may be backfiring. He has accused her of mismanaging the economy and standing by as a corruption scandal rocked Brazil's largest company, state-run oil producer Petroleo Brasileiro, but neither issue seems to be changing many voters' minds.
Instead, Brazilians who are turned off by the negative tone of the presidential campaign have been increasingly blaming Neves. Datafolha found 36 percent thought he was running the more aggressive campaign, compared with 24 percent who thought so of Rousseff.
(Additional reporting by Brad Haynes; Editing by Todd Benson and Lisa Von Ahn)