David Roth's commanding 91.5% implied probability in the Idaho Democratic U.S. Senate primary on May 19 stems from his status as the party establishment choice, bolstered by prior 2022 nomination experience, active campaigning, and recent endorsements from groups like Madison County Democrats and Progressive Voter Network. In this low-turnout contest open to unaffiliated voters, challengers Brad Moore and Nickolas Bonds lag with minimal visibility, fundraising, and organizational support amid sparse media coverage and no public polls. Absentee requests closed May 8 with no signs of upset momentum; traders see little risk to Roth barring a late scandal, major defection, or ballot controversy in the final days.