Tens of millions of low-income Americans will soon have to show their birth certificates or U.S. passports if they want to obtain health care through their state Medicaid programs.

The requirement that beneficiaries provide proof of citizenship goes into effect July 1. It's designed to root out cases of illegal immigrants getting their health care paid for by the government.

Health analysts say they fear the provision could prevent some citizens from getting health care.

Advocacy groups for the homeless and mentally ill have asked the Bush administration to presume that beneficiaries seeking care are eligible for the health insurance program for the poor. Then, they would be given time to get the necessary documents.

"They may not have kept the best records, particularly those with serious mental health disorders," said Kirsten Beronio, senior director of government affairs for the National Mental Health Association. "For them, there needs to be some accommodations made that other types of records could be used."

Mark McClellan, administrator for the Centers for Medicare and Medicaid Services, said he was sensitive to the concerns cited by various consumer groups. He said the agency was crafting a process for exceptions.

"We want to provide a reasonable amount of leeway," McClellan said. "Not everyone, at least in a timely way, can produce one of the statutory documents. We do expect that the vast majority of people will have little difficulty given enough time. We want to make sure we have processes that can work for others."

He did not provide specifics about how much time beneficiaries may be given to gather documents, or what other types of documents might be allowed. He said such guidance will be issued to the states soon.

"The challenge in the Medicaid program is making sure the dollars go where they're intended to go without imposing any undue burdens on states and beneficiaries," McClellan said. "That's what we're looking for here."

The citizenship requirement was attached to a bill that President Bush signed into law in February spelling out $35 billion in spending cuts over a five-year period. Much of the focus was on slowing the growth in Medicaid.

The provision will save federal taxpayers an estimated $220 million over the next five years, according to the Congressional Budget Office.

Last year, the inspector general for the Department of Health and Human Services found that a majority of states don't verify claims of U.S. citizenship by those seeking Medicaid. The practice creates the potential for illegal immigrants to access the health care program.

The inspector general's report did not address to what extent there is a problem with illegal immigrants accessing Medicaid, only that the potential exists.

Federal law says a person must be a citizen to receive Medicaid benefits. However, emergency care cannot be denied.

States now can accept a signed declaration as proof of U.S. citizenship. Forty-six states do.

Only Montana, New York, New Hampshire and Texas require applicants to submit documents verifying citizenship.

The bill required that Medicaid applicants show a birth certificate or U.S. passport but gives the administration leeway in saying other documents could be acceptable. An example might be a sworn affidavit that describes why documentary evidence does not exist or cannot be obtained.

Directors of community health centers, which specialize in helping the poor access health care, have asked the administration to accept as proof of citizenship report cards, voter registration cards, tribal documents and military ID cards.

The Center on Budget and Policy Priorities, a liberal think tank, said disaster victims and elderly African-Americans may have difficulty accessing records such as birth certificates. Several black lawmakers have signed onto bills that would repeal the proof of citizenship requirement for participating in Medicaid.

The group said many elderly blacks were born in a time when racial discrimination in hospital admissions kept their mothers from giving birth at hospitals, so their births often were not officially registered. The center conducted a survey showing 9 percent of black adults reported they lack a passport or birth certificate, compared to 5.7 percent of all adults surveyed.

The new requirement will apply to all Medicaid applications submitted after July 1, as well as all applications to renew Medicaid coverage.