One thing I've always thought is that it is easier to be a legislative majorities if there are less open seats. There have always been democrats in marginal seats who are personally popular but with the possibility of their seat going republican if they had retired. In this thread we will name some senators or reps and speculate if they would still be in office had they not retired (meaning would they keep getting re-elected)
I'll start with the following:
Senate
George Mitchell
John Glenn
Evan Bayh
Richard Bryan
Dennis DeConcini
David Boren
Dale Bumpers
John Breaux
Bob Graham
Sam Nunn
House
Paul Hodes
Stan Lundine (represented SW NY Seat, ran for Lt Gov in 86)
Bob Edgar (represented Del Co seat, ran for senate in 86)
Ted Strickland
Tom Luken (represented Cincy area in 80s)
Doug Applegate
Lee Hamilton
Brad Ellsworth
Bart Stupak
Howard Wolpe
of course those are a few off the top of my head. Feel free to name some more.