This class of senators was elected in the November 2016 and sworn in Jan. 3, 2017.

The Republican seats that will be up for re-election are:

Roy Blunt, (MO);

John Boozman, (AR);

Mike Crapo, (ID);

Chuck Grassley, (IA);

John Hoeven, (ND);

Ron Johnson, (WI);

John Kennedy, (LA);

James Lankford, (OK);

Mike Lee, (UT);

Jerry Moran, (KS);

Lisa Murkowski, (AK);

Rand Paul, (KY);

Marco Rubio, (FL);

Tim Scott, (SC);

Richard Shelby, (AL);

John Thune, (SD);

and Todd Young, (IN).