Community clinics, which typically provide primary but not specialty care, have expanded and hired more medical staff members to meet the anticipated wave of new patients. And managed-care companies are recruiting doctors, nurse practitioners and other professionals into their networks, sometimes offering higher pay if they improve care while keeping costs down. But it is far from clear that the demand can be met, experts say.

In California, with the nation’s largest Medicaid population, many doctors say they are already overwhelmed and are unable to take on more low-income patients. Dr. Hector Flores, a primary care doctor in East Los Angeles whose practice has 26,000 patients, more than a third of whom are on Medicaid, said he could accommodate an additional 1,000 Medicaid patients at most.

“There could easily be 10,000 patients looking for us, and we’re just not going to be able to serve them,” said Dr. Flores, who is also the chairman of the family medicine department at White Memorial Medical Center in Los Angeles.

California officials say they are confident that access will not be an issue. But the state is expecting to add as many as two million people to its Medicaid rolls over the next two years — far more than any other state. They will be joining more than seven million people who are already in the program here. One million of the newly eligible will probably be enrolled by July 2014, said Mari Cantwell, an official with the state’s Department of Health Care Services.

On top of that, only about 57 percent of doctors in California accept new Medicaid patients, according to a study published last year in the journal Health Affairs — the second-lowest rate in the nation after New Jersey. Payment rates for Medicaid, known in California as Medi-Cal, are also low here compared with most states, and are being cut by an additional 10 percent in some cases just as the expansion begins.