You need to review your constitutional law. The practice of pharmacy (and indeed the regulation of all professions, including scope of practice, is a STATE issue). This is why we have 50 state BOPs, and why we must undergo a separate license process in each state we want to practice in. There are some areas where state/federal oversight overlap (DEA, FDA) but states are still free to make laws that are MORE restrictive than federal law. Then tension comes when states seek to decriminalize behavior that's constrained by federal law (such as medical marijuana). But for the majority of legal matters pertaining to pharmacy, we look not to "Capitol Hill" but to our individual state legislatures.
I'll ask again, if the AMA is so powerful, why do pharmacists have immunization rights in many states? They didn't seem to be able to block that, did they? And pharmacists already have limited prescriptive authority in a number of situations.
You're ascribing way too much power to the AMA, and you show a basic lack of understanding of how professions are regulated and governed.