SAN FRANCISCO – This city is once again at the political vanguard, launching a bold and unprecedented program to ensure health care coverage for every one of San Francisco’s residents.

“It’s historic not only for this city and for this county. It’s historic for the state and arguably it’s historic for the country,” Mayor Newsom said in announcing the plan on Tuesday. “This city is going to be the first city in America with universal health access…. I look forward to being an envy of the rest of the nation.”

The new plan is projected to cover 82,000 uninsured San Franciscans at a cost of approximately $203 million annually. More than half of the funding would come from existing city expenditures on care for the uninsured. Participants in the program would pay a premium of $3 to $201 a month, depending on income, Mr. Newsom said.

“It’s achievable,” the mayor said. “This is not a pipe dream.”

The program also calls for a mandatory contribution from businesses that do not currently provide health insurance for their employees. The details of the mandate are still being negotiated, but one city supervisor has proposed a fee of $1 to $1.60 an hour on payrolls of businesses with more than 20 employees and no health plan.

San Francisco’s move toward universal health care is the latest indicator that state and local officials are pushing to address the problem of the uninsured as reform of the health care system remains on the back burner in Washington.

“San Francisco is not waiting around for new federal constructs or mandates, or state constructs or mandates. San Francisco is moving forward to fulfill its moral obligation,” Mr. Newsom said.

In April, Massachusetts passed legislation that would move toward a so-called individual mandate, under which residents are required to purchase some health insurance. While Mr. Newsom is a liberal Democrat, Governor Romney of Massachusetts, who pushed for that state’s plan, is a Republican with conservative stances on most issues.

A spokesman for a national group that lobbies for greater health coverage, Families USA, said the localized efforts are a measure of frustration with Washington policy-makers. “A number of states and perhaps some cities now are saying we don’t want to sit idly by while nothing occurs. It really is an absence of leadership,” the director of Families USA, Ron Pollack, said.

Still, Mr. Pollack acknowledged that efforts to deal with health care issues on a local level face serious obstacles. “There’s no doubt as you go on down the line it is tougher to take meaningful action,” he said.

An analyst with a libertarian think tank in San Francisco, the Pacific Research Institute, said the city could be left in the financial lurch by the plan’s central assumption, that open access to clinics and doctors’ offices will reduce spending on emergency room care.

“Failing any price incentives, it’s very difficult to predict how and where people will go for care,” the analyst, John Graham, said. “I don’t think the fact that you’re going to get everything for free means people are going to make the right decision.”

Mr. Graham said he is sympathetic to what he views as Mr. Newsom’s effort to address a problem for which he is not responsible. “The reason why people are uninsured is because health insurance is too expensive,” he said. Mr. Graham added that he attributes the situation to heavy regulation at the state and federal level.

The issue was raised indirectly as Mr. Newsom unveiled his plan. He repeatedly referred to the new program as insurance, but documents distributed to reporters said the plan is not insurance.

The city’s director of public health, Dr. Mitchell Katz, said the change in nomenclature “enabled us to avoid certain charges.” He did not elaborate.

Dr. Katz said one reason the program was financially viable in San Francisco but might not be in other cities is that San Francisco has traditionally offered a more generous amount of free care to the uninsured.

Mr. Newsom was elected in 2003 on a platform that called for reducing cash welfare compensation that, in the eyes of many voters, made the city a magnet for the homeless. Critics warned yesterday that the health care plan could have much the same effect by attracting the sick and uninsured.

“I can see a kind of death spiral,” Mr. Graham said. “You have a lot of sick people wanting to come in and a lot of businesses wanting to get out.”

A spokesman for Mr. Newsom, Peter Ragone, said residency requirements would be strictly enforced. He also said San Francisco’s expensive cost of living makes it unlikely people would move to the city for the health coverage. “Our feeling is that would be a wild exception to the rule. People are just not going to do that,” Mr. Ragone said. “If they do, we’ll put a stop to it.”