South Dakota primaries heat up with governor showdown, Senate race and Sioux Falls mayoral bid

South Dakota voters will cast GOP nominations for governor (Rhoden vs. Johnson, Hansen, Doeden), U.S. Senate (Rounds vs. McNeal) and U.S. House (Jackley vs. Bialota), plus a Sioux Falls mayoral race; Democrat Dan Ahlers is unopposed for the Democratic nomination for governor. A 35% threshold could trigger a June 23 runoff, and independents may participate in the Democratic primary while party rules limit participation in the Republican primary.