Who is John Thune, the next Senate majority leader?

The election of Republican John Thune of South Dakota as Senate majority leader tasks a key ally of Mitch McConnell with shepherding the agenda of President-elect Donald Trump through Congress.

​ The election of Republican John Thune of South Dakota as Senate majority leader tasks a key ally of Mitch McConnell with shepherding the agenda of President-elect Donald Trump through Congress. Read More Breaking News, Latest News and Videos | CNN