The AMA supported Obama and his plan
The AMA has long ceased to be an organization that represents the views of the "grassroots" of American doctors. Less than 20% of all American doctors are currently members, quite a contrast to the time when a significant majority were (and the AMA opposed socialized medicine and Medicare). That small percentage of physicians who are currently affiliated with the AMA tend to be government employees and academics largely funded by government.
The AMA derives a substantial chunk of its income nowadays from a cozy "copyright" arrangement with the federal government on Medicare billing codes. These code books produced and copyrighted by the AMA are sold to doctors' offices. By government fiat, the Medicare codes contained in them must be used in order for those offices to bill Medicare for physicans and other services. Thus the medical practices are coerced into buying a product from the AMA if they want to bill Medicare. (The same AMA codes are used for other insurance billing as well.) The AMA has in effect a government-granted monopoly in this area, and its business with the billing codes only figures to expand if Obamacare is not repealed.
And membership in the AMA dropped like crazy. I think the AMA has only about 17% of all docs in the USA as members.
As did the pharmaceutical industry and the AARP. Even though the individual members of all, on the whole, will be negatively effected by Obamacare. But the government made them (the industry groups) an offer they couldn't refuse. AARP stands to make BILLIONS from "supplemental insurance" they'll broker to their members. The pharmaceutical industry seems to have received certain "guarantees" from the government, what they are, we don't know yet, nor do the companies really know if the government will keep its promises. Same with the AMA.
All have made Faustian bargains for their own selfish reasons, and they just have to hope they'll be the last eaten by the crocodiles they're feeding.
Mark