**The Rio de Janeiro Senate race for the two seats up in the October 4, 2026 election remains tightly contested among a fragmented field of roughly 16 registered candidates.** Polls released in July and early August place Benedita da Silva (PT) in the lead for the top spot, with Marcelo Crivella (Republicanos) competitive for second and Pedro Paulo (PSD), Carlos Jordy (PL), and Carlos Portinho (PL) clustered closely behind. Recent finalization of candidacies on August 15 has clarified the ballot but introduced little separation, as no major withdrawals or consolidations have occurred and voter intentions show high indecision or split preferences across parties. **The market’s narrow spreads reflect this multi-candidate dynamic in an open-seat contest formerly held by Flávio Bolsonaro (now running for president).** Key variables that could widen gaps include upcoming Datafolha or AtlasIntel releases measuring first- and second-place intentions, any late alliances or endorsements from state-level figures, and turnout patterns in the capital versus interior municipalities. With the vote less than two months away, modest shifts in name recognition or campaign visibility among the mid-tier contenders could still reorder the top tier before election night.