Will Flávio Bolsonaro win the second round of the 2026 Brazilian presidential election by 4–8%?

ResolutionResolved NO

YES payout0¢

NO payout100¢

VenuePolymarket

Realized · held to resolution+56%$100 paper stake

Polymarket36¢ → 0¢

Our position · NO64¢ → 100¢

Signal endedOct 26

Forecast updated

Oct 20 forecast

YES: Q 33.9% · Market odds 32.5% at forecast

Polling threshold. Several recent national surveys place Bolsonaro leading Lula right at 4 percentage points.

Main caution: Most major surveys show Bolsonaro leading by less than 3 percentage points.

Evidence and updates

Historical precedent. First-round leaders have historically retained their edge to win Brazilian presidential runoffs.

Q updated; quotes are not comparable. Q +3.8 pts since the previous forecast, for YES.

The research packet changed.

Snapshot: 2026-10-20T13:24:47.666707+00:00 · 2026-10-20T13:15:00+00:00.

Ask Q: Will the final Datafolha and AtlasIntel polls published before October 25 show Bolsonaro's valid vote margin reaching at least 4 percent?

Polling threshold

Historical precedent

Political analyst Creomar de Souza noted that historically in Brazil's presidential elections, a second-place candidate from the first round has never managed to overturn the result and win the runoff.

Main caution

Points to NO

The majority of national polling institutes show a margin tighter than 4 percentage points.
Surveys from AtlasIntel, Datafolha, BTG/Nexus, Veritá, and Ipespe published between October 15 and 20, 2026, report Bolsonaro leading by between 0.6 and 2.4 percentage points.
The baseline first-round vote margin was under 2 percentage points.
In the official October 4 first round, Bolsonaro received 47.03% of valid votes versus 45.16% for Lula, an absolute difference of 1.87 points.
Isolated polling continues to show Lula competitive or slightly ahead in valid votes.
The Vox Brasil poll conducted October 15–17, 2026, showed Lula leading Bolsonaro 51% to 49% in valid votes.

Points to YES

Multiple reputable surveys place Bolsonaro's valid vote lead directly at the 4 percentage point threshold.
Polls by Real Time Big Data, PoderData/Aya, and Gerp published between October 18 and 20, 2026, all showed Bolsonaro at 52% to Lula's 48% in valid votes.

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