Not long ago, I attended a meeting on the future of primary care. Most of the physicians in the room knew one another, so the discussion, while serious, remained relaxed.

Toward the end of the hour, one of the physicians who had been mostly silent cleared his throat and raised his hand to speak. The other physicians smiled in acknowledgment as their colleague stood up.

“Nurse practitioners,” he said. “Maybe we need more nurse practitioners in primary care.”

Smiles faded, faces froze and the room fell silent. An outraged doctor, the color in his face rising, stood to bellow at his impertinent colleague. Others joined the fray and side arguments erupted in the back of the room. A couple of people raised their hands to try to bring the meeting back to order, but it was too late.

The physician had mentioned the unmentionable.

I remembered the discord and chaos of that meeting when I read a recent study in The New England Journal of Medicine of nurses’ and physicians’ opinions about primary care providers.

For several years now, health care experts have been issuing warnings about an impending severe shortfall of primary care physicians. Policy makers have suggested that nurse practitioners, nurses who have completed graduate-level studies and up to 700 additional hours of supervised clinical work, could fill the gap.

Already, many of these advanced-practice nurses work as their patients’ principal provider. They make diagnoses, prescribe medications and order and perform diagnostic tests. And since they are reimbursed less than physicians, policy makers are quick to point out, increasing the number of nurse practitioners could lower health care costs.

If only it were that easy.

Three years ago, a national panel of experts recommended that nurses be able to practice “to the full extent of their education and training,” leading medical teams and practices, admitting patients to hospitals and being paid at the same rate as physicians for the same work. But physician organizations opposed many of the specific suggestions, citing a lack of data or well-designed studies to support the recommendations.

In an effort to build consensus, the Robert Wood Johnson Foundation then invited a dozen leaders from national physician and nursing groups to discuss their differences. The hope was that face-to-face discussions would help physicians and nurses understand one another better and see beyond the highly charged and emotional rhetoric. The approach worked, at least initially; after three meetings, the group drafted a report filled with suggestions for reconciling many of the differences.

But an early confidential draft was leaked to the American Medical Association, a group that had not been invited to participate, and the A.M.A. immediately expressed its opposition to the report. Soon after, three of the participating medical organizations — the American Academy of Family Physicians, the American Osteopathic Association and the American Academy of Pediatrics — withdrew their support, and the effort to bring physicians and nurse practitioners together and complete the report collapsed.

Nonetheless, many health care experts remained confident, believing that the large professional organizations had grown out of touch with grass-roots-level health care providers. The guilds might oppose one another, but every day in medical practices, clinics and hospitals across the country, physicians and nurse practitioners were working side by side without bickering. Surely, the experts reasoned, providers who knew and liked one another would be receptive to trying new ways of working together.

Wrong.

Analyzing questionnaires completed by almost 1,000 physicians and nurse practitioners, researchers did find that almost all of the doctors and nurses believed that nurse practitioners should be able to practice to the full extent of their training and that their inclusion in primary care would improve the timeliness of and access to care.

But the agreement ended there. Nurse practitioners believed that they could lead primary care practices and admit patients to a hospital and that they deserved to earn the same amount as doctors for the same work. The physicians disagreed. Many of the doctors said that they provided higher-quality care than their nursing counterparts and that increasing the number of nurse practitioners in primary care would not necessarily improve safety, effectiveness, equity or quality.

A third of the doctors went so far as to state that nurse practitioners would have a detrimental effect on the safety and effectiveness of care.

“These are not just professional differences,” said Karen Donelan, the lead author of the study and a senior scientist at the Mongan Institute for Health Policy at Massachusetts General Hospital in Boston. “This is an interplanetary gulf,” she said, echoing a point in an editorial that accompanied her study.

The findings bode poorly for future policy efforts, since physicians are unlikely to support efforts to increase the responsibilities and numbers of advanced-practice nurses in primary care. And most nurse practitioners are unlikely to support any proposals to expand their roles that do not include equal pay for equal work.

Peter I. Buerhaus, senior author of the study and a professor of nursing at Vanderbilt University Medical Center in Nashville, is chairman of a commission created almost three years ago under the Affordable Care Act to address health care work force issues. But his group has yet to convene because a divided Congress has not approved White House requests for funding.

“We’re running out of time on these issues,” Dr. Buerhaus said. “If the staffing differences remain unresolved, we are just going to cause harm to the public.”

Still, by providing a clearer picture of the extent of these professional differences, the study should help future efforts. “It’s too easy to say that everyone should just get along,” Dr. Donelan said. “These arguments touch on the whole nature of these professions, their core values and how they define themselves.”

“It’s like when family members are warring over a sick patient,” she added. “We need first to acknowledge the others’ position and the full extent of our differences before we can reach any kind of resolution.”