Elevated early and absentee voting is the primary driver of trader positioning around 680K-720K total ballots in Idaho’s November 3 Senate contest. As of October 30, more than 232,000 ballots have already been cast or accepted—exceeding the entire early-vote total from the 2022 midterm—with two days of early voting remaining and strong Republican and unaffiliated participation. Registration growth to roughly 977,000 voters and the presence of independent Todd Achilles challenging incumbent Jim Risch have sustained interest beyond a typical low-turnout midterm, though the race remains rated Solid or Likely Republican. These factors, combined with historical midterm baselines near 595,000 votes and presidential-year peaks above 900,000, explain why markets assign the largest share of probability to turnout in the upper 600K–low 700K range while leaving room for Election Day mobilization to push totals higher.