“...The threat of being primaried can be effective....”
That can be somewhat effective, but the 12’ of rope comment above would certainly straighten out that “spinal issue” with no problem.
Bottom line: They’re gutless whimps only out to look after themselves....UniParty hacks.
Primary them - preferably with a new party - the Federalist party.
They will never change - they must be removed. And anyone elected to replace them should be rotated out on a regular basis.