Flávio Bolsonaro advanced to the October 25 runoff after securing 47.03% of valid votes in the October 4 first round, narrowly ahead of incumbent Luiz Inácio Lula da Silva at 45.16%. Multiple post-election surveys, including AtlasIntel, Datafolha, Ipespe, and PoderData, show the Liberal Party senator leading the runoff by margins of four to six points on valid votes, driven by consolidation of right-wing support from eliminated candidates and voter dissatisfaction with economic conditions under Lula. Jair Bolsonaro remains ineligible due to his prior conviction. Traders on Polymarket have priced Flávio as the clear favorite at 87.3% implied probability, reflecting the consistent polling shift and limited time remaining before the vote.