Brazil’s October 4 Chamber of Deputies election occurs alongside a polarized presidential contest between incumbent Luiz Inácio Lula da Silva and Flávio Bolsonaro of the Liberal Party (PL), with recent polls showing the two statistically tied in runoff simulations. This national polarization, combined with concurrent voting for governors and senators, drives ticket-splitting and coalition strategies that keep multiple center-right and centrist parties competitive for the second-highest seat total behind the likely leader. Economic concerns, corruption scandals, and last-minute judicial rulings on campaign content have further fragmented voter preferences in the final days, sustaining tight implied probabilities across several mid-sized parties. Upcoming vote counting and any late shifts in turnout among right-leaning or anti-incumbent blocs could quickly reorder the lower-house standings once results begin emerging.