N.C. Aizenman / The Washington Post

WASHINGTON — For years, nurses have been subordinate to doctors — both in the exam room and the political arena.

But aided by new allies ranging from AARP to social workers to health-policy experts, nursing groups are pressing ahead in a controversial bid to persuade state lawmakers to shift the balance of power.

In 11 states, they are pushing legislation that would permit nurses with a master’s degree or higher to order and interpret diagnostic tests, prescribe medications and administer treatments without physician oversight. Similar legislation is likely to be introduced soon in three other states.

If the proposals, which face vehement opposition from some physicians’ groups, succeed, the number of states allowing nurses to practice without any type of physician supervision would increase to 30 from 16, in addition to the District of Columbia.

The broader authority being proposed around the country could spur tens of thousands of nurses to set up primary-care practices that would be virtually indistinguishable from those run by doctors.

“We have a ready-made, no-added-cost workforce in place that could be providing care at a much higher level if we modernize our state laws,” said Taynin Kopanos, director of health policy and state issues for the American Association of Nurse Practitioners.

“So the question for states is, are you going to fully deploy this resource or not?” Kopanos continued.

The nurses’ last big legislative push, a state-by-state effort that began in the late 1980s, sputtered by the early 1990s. This time, however, the campaign is being coordinated nationally by the AANP and other nursing groups and is getting a critical boost from consumer advocates and state officials concerned about the 2010 health care law’s looming impact on the availability of doctors.

Beginning in January, about 27 million uninsured Americans are expected to get coverage under the law, contributing to a projected shortage of about 45,000 primary-care physicians by 2020, according to the Association of American Medical Colleges.

Claudio Gualtieri of AARP’s Connecticut branch said it makes sense to empower qualified nurses to step into the breach. “These are actually good ideas that we should have put into practice a long time ago,” he said. “But now, with the timetable for the health care law rolling out, there’s an extra impetus to do so.”

The nurses have won the support of faith-based organizations, social workers, patients’ groups and the National Governors Association. Perhaps the most valuable endorsement came from experts convened by the National Academy of Sciences’ prestigious Institute of Medicine.

The health care law itself encourages the creation of nurse-run practices by requiring insurers to pay nurses the same rates they pay doctors for the same services, starting next year. (Medicare, however, will still reimburse nurses at 85 percent of the doctors’ rate.)

But even some state lawmakers who are sympathetic to the nursing groups’ proposals are reluctant to give up on the Normal Rockwell-esque model of a venerable M.D. serving as the steward of a family’s health.

“My worry is that we will be lowering the standard of care,” said Kentucky state Sen. John Schickel, a Republican. He said that he is being lobbied heavily by all sides.

Physician groups have fueled lawmakers’ concerns by emphasizing the differences in education between doctors and “advanced practice nurses,” which include nurse practitioners specializing in primary care.

Such nurses get a bachelor’s degree in nursing, then spend 2 1/2 to three years studying for a master’s degree. One more year of study is needed to get a Ph.D, which will be required of all newly minted nurse practitioners beginning in 2015. No residency or further training is required.

Physicians must get a bachelor’s degree that typically includes various science courses, then spend four years in medical school, followed by at least another three years in a residency program.

That extra training means family doctors are equipped to recognize unusual circumstances that nurse practitioners might miss, said Reid Blackwelder, president-elect of the American Academy of Family Physicians.

Physicians’ groups also complain that nurse-only practices will further splinter a health care system that many experts say needs to be more coordinated.

“Team care, in which each member is doing what they have been trained to do best, is really what’s going to produce greater efficiency and greater quality of care,” said Ardis Dee Hoven, president-elect of the American Medical Association.

Nurse practitioners say that they are eager to work in teams with physicians but that this is impractical where doctors are in short supply, such as rural and low-income communities. And they contend their training, which emphasizes a holistic approach, makes them just as capable as doctors in catching problems.