Nikki Gronli leads trader consensus at 47.5% implied probability in the South Dakota at-large Democratic primary, driven by her frontrunner status in recent polling and fundraising dominance as a sitting state representative. A May South Dakota News Watch poll showed her at 42% support, far ahead of Scott Schlager's 12%, reflecting her endorsements from county parties and legislative experience appealing to base voters. Schlager's 7.5% odds stem from grassroots activism on progressive issues, though limited funds cap his upside. Billy Mawhiney's 2% reflects minimal visibility despite business background. With the June 4 primary nearing, low Democratic turnout adds uncertainty, but Gronli's momentum sustains her edge in this sparse field.