Brazil Election Second Round Margin prediction

Flávio Bolsonaro finished the first round on 47.03% against 45.16% for Lula, a result that defied pre-election polls showing the president ahead. That gap of under two points is the strongest case for a tight runoff on 25 October. The first Datafolha runoff poll, with fieldwork on 6 and 7 October, put Bolsonaro on 49% and Lula on 45%. In valid votes it was 52% to 48%, which is exactly four points. The pollster called it a technical tie at the edge of the 2-point margin of error, with Bolsonaro more likely ahead. A snapshot is not a result, and it is the only post-first-round poll in the record. The forecast leans against a Bolsonaro win by less than four points because several outcomes fall outside that bracket. A margin of exactly four counts as the higher bracket. Lula could also win if the race tightens and flips. Reports indicate conservative rivals have begun endorsing Bolsonaro, and about 9 million first-round votes went to other candidates, so a wider win is possible. The narrow-win bracket is still the single most likely Bolsonaro scenario. It needs only slight tightening from the Datafolha figures. The thing to watch is the next round of polling. If valid-vote margins settle clearly above or below four points, the picture will change fast.