**PL maintains a clear lead in trader expectations for the most seats in Brazil’s Chamber of Deputies** due to its position as the largest current caucus (98 seats) and its established organizational strength ahead of the October 4, 2026, vote. Open-list proportional representation across states rewards parties with broad geographic reach, disciplined candidate slates, and reliable voter bases—advantages PL holds through its alignment with conservative, evangelical, and agribusiness constituencies. UPB (likely referencing the UNIÃO bloc or allied centrist grouping) trails at roughly one-third probability because it lacks comparable national cohesion despite holding the second- or third-largest current presence. Smaller parties and left-leaning coalitions such as FE Brasil remain marginal in the market, reflecting fragmented opposition and the challenges of converting presidential polarization into legislative seat gains under the current system. With roughly seven weeks remaining, the market pricing captures the view that recent stability in PL’s congressional position and the broader right-wing mobilization around the presidential contest have not been disrupted by major late developments. Key variables that could still shift probabilities include final candidate registrations, coalition negotiations among Centrão parties, and state-level turnout dynamics in the proportional contests.