Those who don't should be exposed for the useless seat-fillers they are. They would be defeated in short order in the next election. An enemy you know in the seat is preferable to a 'friend' that abandons you when his vote is most needed.
We have a cultural problem in some of the jurisdictions that are sending these RINOs up, especially New England. Our best bet is to work to flip the rest of the "Ds" to "Rs" in the red states.