**The second-round contest on October 25 between Flávio Bolsonaro and incumbent Luiz Inácio Lula da Silva features two candidates with deep national bases and high mobilization capacity.** First-round results produced 119.3 million valid votes, with Flávio at 56.1 million and Lula at 53.9 million amid 78.9% turnout. The all-time record stands at 60.3 million from the 2022 runoff. Brazil’s electorate has grown modestly since then, and the polarized matchup—bolstered by compulsory voting for most adults—typically lifts second-round participation and valid ballots. Recent post-first-round polling shows a competitive race within margins of error, spurring both sides to maximize turnout. Traders assign 90% probability to Yes because these structural and campaign dynamics make surpassing the prior peak the most likely outcome, though final totals hinge on abstention rates and vote consolidation from eliminated candidates.