AUGUSTA, Maine » With Republicans in complete control of Maine’s state government for the first time since 1962, state Sen. Lois A. Snowe-Mello offered a bill in February to limit doctors’ liability that she was sure the powerful doctors’ lobby would cheer. Instead, it asked her to shelve the measure.

"It was like a slap in the face," said Snowe-Mello, who describes herself as a conservative Republican. "The doctors in this state are increasingly going left."

Doctors were once overwhelmingly male and usually owned their own practices. They generally favored lower taxes and regularly fought lawyers to restrict patient lawsuits. Ronald Reagan came to national political prominence in part by railing against "socialized medicine" on doctors’ behalf.

But doctors are changing. They are abandoning their own practices and taking salaried jobs in hospitals, particularly in the North, but increasingly in the South as well. Half of all younger doctors are women, and that share is likely to grow.

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 Barack 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 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 environmental concerns like chemicals in baby products.

Even the issue of liability, while still important to the AMA and many of its state affiliates, is losing some of its unifying power because malpractice insurance is generally provided when doctors join hospital staffs.

"It was a comfortable fit 30 years ago representing physicians and being an active Republican," said Gordon H. Smith, executive vice president of the Maine Medical Association. "The fit is considerably less comfortable today."

Three years ago, Smith found himself leading an effort to preserve a beverage tax — a position anathema to his old allies at the Maine State Chamber of Commerce and the Republican Party but supported by doctors because it paid for a health program. The doctors lost by a wide margin, and the tax was overturned.

Smith still goes to the state Capitol wearing gray suits, black wingtips and a gold name badge, but he increasingly finds himself among allies far more casually dressed, including the Maine People’s Alliance and labor groups. And while he still greets old Republican friends — he is a lobbyist, after all — he spends much of his time strategizing with Democrats.

Rep. Sharon Anglin Treat, a powerful Democrat who was first elected in 1990, said that she and Smith were once bitter foes. "But Gordon’s become like a consumer activist," she said with a big smile. "I’ve seen him more times in the last few years than I can count."

Dr. Lee Thibodeau, 59, a neurosurgeon from Portland, still calls himself a conservative but says he has changed, too. He used to pay nearly $85,000 a year for malpractice insurance and was among the most politically active doctors in the state on the issue of liability. Then, in 2006, he sold his practice, took a job with a local health care system, stopped paying the insurance premiums and ended his advocacy on the issue.

"It’s not my priority anymore," Thibodeau said. "I think Gordon and I are now fighting for all of the same things, and that’s to optimize the patient experience."

Many of Smith’s counterparts in other states told similar stories of change.

"When I came here, it was an old boys’ club of conservative Republicans," said Joanne K. Bryson, executive director of the Oregon Medical Association since 2004.

Now her group lobbies for public health issues that it long ignored, like insurance coverage for people with disabilities.

Even in Texas, where three-quarters of doctors said last year that they opposed the new health law, employed doctors were twice as likely as those who owned a practice to support the overhaul, as were female doctors.

Dr. Cecil B. Wilson, president of the AMA, said that changes in doctors’ practice-ownership status do not necessarily lead to changes in their politics. And some leaders of state medical associations predicted that the changes would be fleeting.

Dr. Kevin S. Flanigan, a former president of the Maine Medical Association, described himself as "very conservative" and said he was fighting to bring the group "back to where I think it belongs." Flanigan was recently forced to close his own practice, and he now works for a company with hundreds of urgent-care centers. He said that in his experience, conservatives prefer owning their own businesses.

"People who are conservative by nature are not going to go into the profession," he said, "because medicine is not about running your own shop anymore."