Nikki Gronli leads trader consensus at 55.5% implied probability to win South Dakota's at-large U.S. House Democratic primary on June 2, bolstered by the state Democratic Party's endorsement on April 14, which highlighted her record as former USDA Rural Development state director and small business owner focused on rural issues key to the district. Scott Schlagel holds 33.5% as an early filer and Dell Rapids correctional officer appealing to working-class voters, setting up a contested race amid low Democratic turnout expectations. Billy Mawhiney's 2.5% reflects his February suspension of candidacy after initial nonprofit executive bid. Absent polls, odds hinge on endorsements and name recognition in this open primary against Republican incumbent Dusty Johnson.