Roll back Medicare Part D? That specific of a proposal would go over like a led balloon. That's why it hasn't been discussed. Instead Republican Congressman Ryan's proposed budget calls for turning Medicare into block grants.
Folks might say, "okay," they don't understand what block grant means anyway. They'll say, between cans of beer with the football game playing in the background, "whatever."
Block grants. Kind of an esoteric topic. The Ryan budget did go over like a led balloon anyway.
Rolling back a specific benefit, like the drug benefit, or raising the copay would certainly make people upset. They'd understand that even better.