1. John Barrasso (R-WY)
2. Roy Blunt (R-MO)
3. John Boozman (R-AR)
4. Tom Coburn (R-OK)
5. John Cornyn (R-TX)
6. Mike Enzi (R-WY)
7. Lindsey Graham (R-SC)
8. Chuck Grassley (R-IA)
9. Orrin Hatch (R-UT)
10. Jim Inhofe (R-OK)
11. Mike Johanns (R-NE)
12. Ron Johnson (R-WI)
13. Mike Lee (R-UT)
14. Ted Cruz (R-TX)
15. Mitch McConnell (R-KY)
16. Rand Paul (R-KY)
17. Jim Risch (R-ID)
18. Pat Roberts (R-KS)
19. Marco Rubio (R-FL)
20. Tim Scott (R-SC)
21. Jeff Sessions (R-AL)
22. John Thune (R-SD)
(h/t to Think Progress for pointing out the trend)