4 more come from swing or Democratic-leaning states:
Sens. Charles Grassley (Iowa), Dean Heller (Nev.), Ron Johnson (Wis.), and Pat Toomey (Pa.)
2 face notable primary opposition in red states:
Sens. Mike Enzi (Wyo.) (from Liz Cheney) and Pat Roberts (Kan.) (from President Obama's second cousin, Milton Wolf)
9 more come from reliably red states:
Sens. Tom Coburn (Okla.), John Cornyn (Tex.), Mike Crapo (Idaho), Mike Lee (Utah), Jim Risch (Idaho), , Tim Scott (S.C.), Jeff Sessions (Ala.), Richard Shelby (Ala.), and David Vitter (La.).
1 other red-state Senate Republican did not vote following heart surgery:
Sen. James Inhofe (R-Okla.)