South Dakota Sen. John Thune jumps into race to succeed McConnell as Senate leader

South Dakota Sen. John Thune is entering the race to be the next Republican leader of the U.S. Senate after Sen. Mitch McConnell steps away from the post in November

​ABC News: US South Dakota Sen. John Thune is entering the race to be the next Republican leader of the U.S. Senate after Sen. Mitch McConnell steps away from the post in November