Supporters of the expansion say that having more doctors will improve care, by getting doctors to urban and rural areas where they are needed, by shifting care to primary and family practice physicians rather than expensive specialists, and by reducing long waits for people to see a doctor and get the care they need.

But skeptics say that although many parts of the country do need more primary care, American doctors tend to congregate in affluent, urban and suburban areas that already have a generous supply.

They say that doctors create demand for their own services, and that nurse practitioners and physician assistants could fill gaps in medical care at a lower cost.

“When you add more physicians to an area, they just add more services, and their salaries don’t go down anywhere near in proportion to the increased supply,” said Dr. David Goodman, professor of pediatrics at the Dartmouth Institute for Health Policy and Clinical Practice and a practicing physician who has studied work force issues for 20 years. “More care may not be better, but it certainly is paid for,” Dr. Goodman said.

Many of the developing medical schools are well aware of such arguments, and are billing themselves as different from traditional medical schools, more focused on serving primary care needs in immigrant and disadvantaged communities. Administrators say that they expect that approach to be buttressed by a shift in state and federal reimbursements from specialists to primary care doctors.

Riverside County, an inland area with a diverse population including immigrants and Native Americans that has expanded rapidly, has a deficit of about 3,000 physicians, according to Dr. G. Richard Olds, founding dean of the University of California, Riverside School of Medicine.

Riverside has applied for licensing, the first step toward becoming a medical school, and hopes to admit its first four-year class in 2012, and to have 400 students by 2016, a typical size for the new crop of schools. Dr. Olds said his educational focus, building on his background as a tropical disease specialist, would be on prevention and “wellness.”