PL leads the market at 85.5% because it already holds the largest bloc in the Federal Senate (16 of 81 seats) ahead of the October 4, 2026 election, when 27 seats are contested under Brazil’s staggered majoritarian system. Right-leaning momentum, anchored by the Liberal Party’s alignment with the Bolsonaro movement and Flávio Bolsonaro’s Senate candidacy, supports expectations of further gains or retention of the plurality. Center and center-right parties such as MDB, PP, and PSD trail because they lack comparable current representation or unified national tailwinds. Recent presidential polling showing a competitive race between incumbent Lula (PT) and opposition figures has reinforced trader consensus that PL’s congressional positioning remains durable, with limited scope for any single rival to surpass it by election night.