In Idaho’s 2026 U.S. Senate contest, trader consensus on total ballots cast remains tightly clustered because a heavily favored Republican incumbent faces an independent challenger after the Democratic nominee withdrew, reducing the contest’s competitive intensity. Recent primary participation exceeded historical averages near 30 percent, driven by population growth and higher registration, yet the race’s safe status typically caps general-election mobilization compared with battlegrounds. Early voting volumes, get-out-the-vote spending by both sides, and any late national developments could lift or suppress participation across the 560K–720K range that currently draws the strongest implied probabilities.