Brazilian Sen. Flávio Bolsonaro leads President Luiz Inácio Lula da Silva ahead of the country’s October 25 presidential runoff, according to a new Datafolha poll released Wednesday.

Bolsonaro, the son of former Brazilian President Jair Bolsonaro and a member of the right-wing Liberal Party, received 52% of valid votes in the survey, compared with 48% for Lula, who is seeking reelection. Brazil determines its presidential winner based on valid votes, excluding blank and spoiled ballots.

When all responses were included, Flávio Bolsonaro led Lula 49% to 45%. Another 5% said they planned to cast a blank or spoiled ballot, while 1% remained undecided.

The poll marks the first major survey since Sunday's first round, when Bolsonaro finished ahead of Lula with more than 56 million votes. Lula, the longtime leader of the leftist Workers' Party, received approximately 53.8 million votes but fell short of securing another term outright, forcing the contest into a runoff.

Since the first round, Bolsonaro has gained backing from several former presidential candidates and political parties, strengthening his coalition ahead of the decisive vote.

Former candidates Romeu Zema of the Novo party, Ronaldo Caiado of the Social Democratic Party, Augusto Cury of Avante and Clariana Barão of Christian Democracy have endorsed Bolsonaro. The Novo, Podemos and Republicanos parties, along with the União Brasil-Progressistas federation, have also announced their support.

Bolsonaro is additionally seeking support from the centrist Brazilian Democratic Movement, known as MDB. São Paulo Gov. Tarcísio de Freitas, who won reelection Sunday, São Paulo Mayor Ricardo Nunes, and MDB President Baleia Rossi spoke with Bolsonaro by phone Wednesday. The group agreed to meet Tuesday to discuss a possible endorsement.

A separate PoderData/Aya poll also showed Bolsonaro ahead, giving him 49% support to Lula's 44%.

The Datafolha survey questioned 2,520 voters on Tuesday and Wednesday for Folha de S.Paulo and TV Globo. It was registered with Brazil's electoral court and has a margin of error of plus or minus two percentage points.

Lula, 80, is seeking a fourth presidential term after defeating Jair Bolsonaro in the 2022 runoff by fewer than two percentage points, the narrowest margin in Brazil's modern democratic history. The elder Bolsonaro was later barred from seeking office, leaving his son to carry the political movement into the current contest.

With the runoff approaching, the latest polling and a growing list of endorsements give Flávio Bolsonaro momentum heading into the final stretch, although the race remains competitive and the outcome will be decided by voters on October 25.