Correction: A previous version of this article may have left the impression that no clinical training is involved for a master’s degree, but master’s programs include extensive clinical training in addition to classroom work. And, in describing traditional notions of a doctor’s role, the article misspelled the first name of painter Norman Rockwell. This version has been corrected.

Patient Maria Menjiuar gets a thorough exam by nurse practitioner Karen Millett at her home office in Chevy Chase. With the forthcoming implementation of Obamacare in 2014, many states may take another look at granting nurse practitioners the authority to do essentially everything a primary care doctor does.  (Linda Davidson/The Washington Post)

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

But aided by new allies ranging from the AARP to social workers and 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 from 16 to 30, in addition to the District.

Maryland is considered almost in this category as well because the state merely requires a nurse practitioner who wants to operate an independent practice to identify a physician to consult if necessary. By contrast, Virginia is among the most restrictive states, with physician oversight required.

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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. About 6,000 nurses operate independent primary-care practices.

“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?”

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 nurse practioners association 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 the 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 IOM panel, in a report issued in 2010 after the adoption of the health-care law, found no evidence that nurse-run practices were unsafe and concluded that “now is the time” to allow nurses to practice to the full extent of their education and training without limitations by doctors.

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 Norman Rockwell-esque model of a venerable doctor serving as the steward of a family’s health.

“We’re all aging, and we realize that the way medical care has been done for our parents really isn’t working for us,” said Kentucky state Sen. John Schickel (R).

Schickel, chairman of a legislative committee that is considering a bill to expand nurses’ authority, said he often seeks treatment for minor complaints at a clinic at his local drugstore — one that is staffed entirely by nurses. Yet he is hesitant to allow nurses to take on the full range of services involved in a primary practice.

“My worry is that we will be lowering the standard of care,” Schickel said. He said he is being lobbied heavily by all sides. He wants to delay a vote on the bill for more study in the next legislative session.

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 21 / 2 to three years studying for a master’s degree. One more year of study is needed to get a Doctor of Nursing Practice degree, which will be required of all newly minted nurse practitioners beginning in 2015. No residency or further training is required, but master’s programs include extensive clinical training in addition to classroom work.

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.

Whether confronted with a patient whose repeated respiratory infections are actually a symptom of HIV infection or someone with multiple conditions such as hypertension, lung disease and diabetes who comes in with a cough that could indicate a variety of complications, “the family physician simply has the ideal training to take a patient with vague symptoms, look for the big picture and know what’s the best thing to do,” he said.

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.

“We’ve diagnosed breast cancer here, ovarian cancer, prostate cancer,” said Erin Bagshaw, who runs Northwest Nurse Practitioner Associates in the District. “We’ve seen leukemia, severe heart disease, diabetes. We’ve handled emergencies where patients were having a pulmonary embolism and had to go straight to the ER. . . . There’s this fallacy that nurse practitioners can only deal with simple, uncomplicated problems, and it’s just not the case.”

In Maryland, nurse practitioner Karen Millett has carved out a niche serving working-poor Latino immigrants from nearby low-income enclaves through a private practice she runs out of of her Chevy Chase home.

On a recent morning, Millett’s tiny waiting room was filled with the sort of patients who flock to primary-care practices: A Glenmont woman struggling with obesity there to check the progress of her weight-loss program; an Adelphi woman in for her annual Pap smear and physical; an Elk Ridge woman seeking treatment for an ovarian cyst and uterine fibroids.

To accommodate patients who can’t afford to take time off from their jobs, Millett offers extended Saturday hours. Unlike many private physicians, she accepts new Medicaid patients. And for the many who are uninsured, she charges a flat fee of $49 per visit, well below what most primary-care doctors charge.

Millett, 49, whose parents were Peruvian and who has a soft-spoken, motherly manner with her patients, said she considers treating low-income people a personal mission.

But to cover her expenses, she has had to make difficult choices. She supplements her income with work at a hospital every other week, and she has not hired any support staff.

“I do everything, she said, “the booking, the payments — I even clean the bathroom.”