SÃO PAULO—Two new Brazilian presidential election polls on Thursday showed opposition candidate Aécio Neves within striking distance of advancing to a runoff with incumbent President Dilma Rousseff.
Mr. Neves, of the Brazilian Social Democracy Party, would garner 21% of the vote heading into Sunday’s first stage of balloting, according to polling agency Datafolha. That would put him in a statistical tie with Brazilian Socialist Party candidate Marina Silva, who has 24% of the vote. The Datafolha poll, released Thursday evening, has a margin of error of two percentage points.
A second poll, by polling firm Ibope, showed Ms. Silva leading Mr. Neves by a five-percentage-point margin.
Voter surveys show Mr. Neves, the scion of a powerful political family, gaining momentum in recent days. Analysts, including Datafolha’s General Director Mauro Paulino, said Mr. Neves has a real chance to overtake Ms. Silva in Sunday’s balloting, earning the right to face Ms. Rousseff in an Oct. 26 runoff. The nation’s election law requires a runoff if no candidate gets more than half the valid votes in the first round.
Ms. Rousseff still holds a solid lead over her two main challengers. Both the Datafolha and Ibope polls showed her with a 40% share of prospective votes in Sunday’s first-round balloting. The polls predicted she would prevail in the runoff as well. Datafolha shows Ms. Rousseff beating both Ms. Silva and Mr. Neves by a seven-point margin. Ibope showed the incumbent prevailing by seven points over Ms. Silva and 13 points over Mr. Neves.
Brazil’s markets reacted positively ahead of the latest sign of Mr. Neves’s newfound momentum. The benchmark Ibovespa stocks index advanced 1.3% on Thursday, to 53,518 points, the first rise in four sessions. The shares of state-controlled oil company Petroleo Brasileiro SA gained 1.2%, to close at 17.30 reais.
Once considered a lock for runoff against Ms. Rousseff, Mr. Neves was abruptly upstaged by Ms. Silva, who became the head of her party’s ticket when her former running mate, Eduardo Campos, was killed in an Aug. 13 plane crash. Sherocketed to the top of the polls with her display of business-friendly policies, environmental activism and tales of ascent from a family of illiterate Amazon rubber tappers.
But her popularity has withered under television attack ads by Ms. Rousseff, her own missteps and an overtaxed and inexperienced political team.
While Mr. Neves--who was born into a wealthy family of politicians--is gaining ground on Ms. Silva, he so far hasn't proven himself capable of winning the general election. Polls have showed Ms. Rousseff beating him handily in a head-to-head showdown.
But he vowed that could change dramatically in coming weeks in part because of television. Mr. Rousseff so far has held a huge advantage over her rivals, who have enjoyed only a fraction of her TV advertising time. That edge would evaporate in a runoff as the top two candidates would be given equal time.
Speaking to The Wall Street Journal Wednesday at Congonhas Airport on his way to a rally in São Paulo state, Mr. Neves said his strategy is to attack Ms. Rousseff on her handling of Brazil’s economy, which fell into recession in the first half of the year and is bedeviled by a 6.5% inflation. If elected, Mr. Neves has said he would name economist Arminio Fraga, the former head of Brazil’s central bank, as finance minister.
“The economy will have a very large weight,” said Mr. Neves, who is currently a senator and a two-time governor of Minas Gerais state. “If the country doesn’t grow, it does not generate jobs.”
Meanwhile, Mr. Neves is hammering on Ms. Silva in the hopes of slipping past her in Sunday’s balloting. He said he would spend the remaining days campaigning in urban areas, where Ms. Silva has a stronghold.
“Brazil is not for amateurs,” Mr. Neves said, alluding to Ms. Silva’s inexperience.
On Wednesday, during a campaign event in São Paulo, Ms. Silva played down the recent electoral poll results. She vowed to believe she will go to the second round.
“The second round is important as it gives the opportunity to vote twice and to debate twice,” Ms. Silva said, according to the local press.
Marla Dickerson at Marla.Dickerson@wsj.com and Luciana Magalhaes atLuciana.Magalhaes@wsj.com
HONOUR TO CARLA ZAMBELLI (NASRUAS FOUNDER)