Thune, who is 63 and in his fourth Senate term, has promised to work closely with Trump despite differences the two have had over the years.

A look at the three candidates: Thune, 63, defeated then-Senate Majority Leader Tom Daschle in 2004 after arguing during the campaign that Daschle had lost his South Dakota roots during his years in Democratic leadership. Now Thune is running to become majority leader himself.

John Thune’s elevation to Senate Republican leader is being welcomed by many ag, biofuel and conservation groups. No Senate majority or minority leader has come to the job with a background in ag and biofuel policy as deep as the South Dakotan’s since,