As Republicans prepare to take control of the Senate in January, all eyes are on the three-way contest to replace Senate Republican leader Mitch McConnell, who has held the top GOP post for nearly two decades and is stepping down at the end of the year.

Kentucky Sen. Mitch McConnell announced he would step down from his leadership post earlier this year, ending his historic run.

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.