America loves incumbents. Plus of course the campaign finance laws make things more difficult for challengers, it’s harder for them to get money and harder for them to get their message out without that money. Congress has a rate of return of over 90%, in the end Americans prefer the bad penny they know than the penny that might not be bad but they don’t know it.
This is just another of how everyone thinks their own congresscritter\senator is wonderful it the other guys that are bums.
That’s true. Americans may not even vote out their congressmember or Senator in 2018, when the midterm elections always see “Vote out the Bum” voters.
2018 is likely to be a bad year for Democrats, regardless of whether Clinton or Trump wins.
Some voters are just jaded.