| Senator | State | Party | First elected | Reason |
| Barbara Boxer | California | Dem | 1992 | The 4-term liberal icon could go on forever, but at 74 she's had it |
| Dan Coats | Indiana | GOP | 1988, 2010 | He served two terms earlier, retired, came back. Enough already |
| Barbara Mikulsky | Maryland | Dem | 1986 | She would be 87 at the end of another term |
| Harry Reid | Nevada | Dem | 1986 | He's 75 now and didn't relish another bitter campaign |
| Marco Rubio | Florida | GOP | 2010 | He's got bigger fish to fry |
Senate Retirements 2016