There are no national surveys that track doctors’ political leanings, but as more doctors move from business owner to shift worker, their historic alliance with the Republican Party is weakening from Maine as well as South Dakota, Arizona and Oregon, according to doctors’ advocates in those and other states.

That change could have a profound effect on the nation’s health care debate. Indeed, after opposing almost every major health overhaul proposal for nearly a century, the American Medical Association supported President Obama’s legislation last year because the new law would provide health insurance to the vast majority of the nation’s uninsured, improve competition and choice in insurance, and promote prevention and wellness, the group said.

Because so many doctors are no longer in business for themselves, many of the issues that were once priorities for doctors’ groups, like insurance reimbursement, have been displaced by public health and safety concerns, including mandatory seat belt use and chemicals in baby products.