Mato Grosso do Sul voters will select two senators on October 4 under plurality block voting, creating a crowded field where second-place positioning depends on split preferences across right-leaning PL candidates and center-left contenders. Recent August 2026 surveys from Ranking Brasil and Novo Ibrape show Reinaldo Azambuja leading first- and second-preference ballots, with Capitão Contar close behind and Vander Loubet, Soraya Thronicke, and Nelsinho Trad clustered in the mid-teens. Candidacy registrations closed on August 15, locking in roughly ten contenders and limiting late entries that could reorder the pack. Trader consensus remains balanced near 50 percent for most names because no candidate has consolidated a durable advantage, party federations and regional alliances are still fluid, and national trends have yet to produce clear local momentum shifts. Late-campaign polling surges, endorsements from state governors, or turnout differences among rural versus urban blocs could separate the top contenders before election day.