Four Major Polls to Map Brazil's Tightest Presidential Runoff

A crucial barrage of new polling is set to map out the final stretch of Brazil's presidential election, the tightest runoff since the country’s return to democracy in 1985. This week, four major national polling institutes will release fresh surveys, defining campaign strategies and market expectations as Senator Flávio Bolsonaro and incumbent President Luiz Inácio Lula da Silva battle for every vote ahead of the October 25 runoff.

The upcoming data releases follow a highly competitive first round on October 4, where Flávio Bolsonaro—the eldest son of former right-wing President Jair Bolsonaro—defied expectations to lead with 47.04% of the vote. Lula, the 80-year-old veteran leftist currently serving his third presidential term, finished a close second with 45.15%. Because neither candidate crossed the 50% threshold required for an outright victory, they face a high-stakes head-to-head rematch.

Between October 13 and October 15, voters and analysts will dissect numbers from BTG/Nexus, Quaest, Datafolha, and Palver. The first Datafolha survey of the runoff, released on October 8, showed Flávio Bolsonaro technically tied with Lula at 49% to 45% in total votes, which translates to 52% to 48% in valid votes (excluding blank and null ballots). Because the four-point gap sits at the outer limit of the poll's two-percentage-point margin of error, the race remains a statistical toss-up.

The Polling Calendar and Methodologies

The upcoming releases will offer a comprehensive view of the electorate by utilizing different polling methodologies:

• BTG/Nexus (October 13): This telephone-based survey will query 2,000 voters, offering a quick pulse on whether either candidate has gained momentum early in the week.
• Quaest (October 14): Commissioned by media giant Grupo Globo, this poll will feature 2,154 in-person interviews, capturing face-to-face voter sentiment across the country.
• Datafolha (October 15): Considered a gold standard in Brazilian polling, this in-person survey will interview 2,520 people to show whether the initial post-first-round trends are solidifying.
• Palver (October 15): An online survey of 5,000 voters that will provide a massive digital sample of the electorate.

The divergence in methods means observers are looking less at individual numbers and more at the overall trajectory of the race. While Flávio Bolsonaro has successfully built momentum by securing key endorsements from prominent centrist and right-wing governors, Lula is focusing his efforts on mobilizing the millions of Brazilians who abstained in the first round.

What it touches

The extreme closeness of the race directly impacts Brazilian financial markets, where uncertainty over the next administration's fiscal policy has kept investors cautious. State-run giants like oil firm Petrobras (PBR) and public lender Banco do Brasil, alongside the benchmark Ibovespa index, are highly sensitive to shifting polling margins, as a Flávio Bolsonaro victory points toward privatization and deregulation, while a Lula victory signals continued social spending and state-led development.