| RIO DE JANEIRO
RIO DE JANEIRO Brazilian presidential candidate Jose Serra has a last chance to win over voters in a televised debate on Friday night after a new poll showed him trailing by double digits ahead of Sunday's runoff election.
The Datafolha survey released on Friday showed ruling party candidate Dilma Rousseff holding steady with a 10-point lead, dovetailing with other polls showing her on track to become the first woman to be elected Brazil's president.
Serra, of the centrist PSDB party, has a last chance to unsettle the left-leaning Rousseff when they spar in their final campaign debate on the dominant Globo TV network. Coming after a popular soap opera, the debate is likely to attract a large number of viewers -- at least in the opening stages.
But Serra, a 68-year-old former governor of Sao Paulo state, has failed to convincingly win any of the rule-heavy debates so far as Rousseff has fended off his attacks on her lack of experience and alleged involvement in graft scandals.
"At this stage, there's not a lot he can do," said Benedito Tadeu Cesar, a political scientist at the Federal University of Rio Grande do Sul.
Serra needs to balance attacking Rousseff without coming across as too aggressive against his female opponent, which pollsters say can be a turn-off for Brazilian voters.
Rousseff, the 62-year-old candidate of the Workers' Party, has mostly stuck to her trump card -- the booming economy that is the legacy of popular President Luiz Inacio Lula da Silva.
The Globo debate has been an anticipated moment in Brazilian presidential races since 1989, when a poor performance by Lula in his first run for the top job tipped the election in favor of Fernando Collor.
Barring a major corruption scandal, which seems unlikely so close to election day, or a huge collective opinion poll error, the former leftist militant Rousseff appears certain to win.
The survey by Datafolha, regarded as Brazil's most respected polling firm, showed Rousseff with 50 percent of voter support compared to Serra's 40 percent. The previous Datafolha poll on Tuesday showed Rousseff leading Serra by 49 percent to 38 percent.
Rousseff would have a 12-point lead, with 56 percent versus 44 percent for Serra, once blank and void ballots are excluded, as they are on election day, the new Datafolha poll showed. Voting is mandatory in Brazil, although some leave their ballots blank to show dissatisfaction with the candidates.
Rousseff, a career civil servant who was Lula's chief of staff, has regained momentum after a drop in support several weeks ago caused by doubts about her religious beliefs and her alleged involvement in corruption scandals.
Such concerns probably deprived her of an outright victory in the election's first round on October 3.
She has since steered the discussion back to the eight years of strong economic growth under Lula, whose endorsement transformed her from a bureaucrat into a presidential favorite.
Serra faces a separate battle to persuade his supporters that the race is still competitive. His campaign has been entreating people to vote, fearing that a national holiday on Tuesday will tempt many well-to-do Brazilians who are his natural supporters to take a long weekend and skip voting.
If she wins, Rousseff is expected to continue Lula's mix of market-friendly policies and social programs while expanding the role of the state in some areas of the economy.
Datafolha surveyed 4,205 people on Thursday for the poll, which had a margin of error of 2 percentage points. Five percent plan to submit blank votes or not vote for either candidate, while 4 percent were undecided.
(Additional reporting by Brian Ellsworth in Rio and Hugo Bachega in Sao Paulo; Editing by Todd Benson and Vicki Allen)