Rui Costa (PT) holds an 88.5% implied probability of finishing first in the Bahia Senate race, reflecting consistent leads in late-September polling from AtlasIntel, Real Time Big Data, and Quaest. As a former two-term governor and recent Casa Civil minister, Costa benefits from high statewide name recognition and alignment with the governing PT coalition backing Jerônimo Rodrigues for governor. Voters select two senators on October 4, and surveys place Costa ahead of running mate Jaques Wagner (6.5%) and opposition figures João Roma (PL) and Angelo Coronel (Republicanos), who trail in first-place scenarios despite competing for the second seat. Recent surveys show minimal movement in the final week before voting, with undecided and blank votes remaining elevated but not enough to shift the top-position consensus among traders.