The cards would be accepted by all city agencies and organizations that receive city funding. Ammiano plans to introduce the legislation within a couple of weeks. He also is trying to persuade financial institutions to allow residents to use the cards to open accounts.

"There is a large community who contribute, and there are not a lot of safeguards around their (immigration) status, their peace of mind and their ability to participate," Ammiano said, adding that the card would be available to all people living in San Francisco regardless of their immigration status.

San Francisco could be the first large American city to have such a card. New Haven, Conn., has such a program, and New York City is considering one.

Ammiano said the impetus for the city cards came from the immigrant community, which asked for his help. Illegal immigrants who are victims or witnesses of crime often do not report the incident because they have no identification and fear deportation. Identification also is needed for many services, such as city health care.

San Francisco already has a sanctuary policy for immigrants, which means no city agency, including the police, will assist the federal government to deport people. So-called sanctuary cities have become a major issue among Republican presidential candidates.

Mitt Romney, the former governor of Massachusetts, has been attacking former New York Mayor Rudy Giuliani - including during a debate Wednesday night - over his city's sanctuary status. Romney broadcast a radio advertisement in Iowa and New Hampshire, where a voice-over states, "Immigration laws don't work if they're not enforced. That's the problem with cities like Newark, San Francisco and New York."

Later in the ad, Romney himself says that as president he would "cut back federal funds to cities that provide sanctuary to illegal immigrants," a pledge he repeated at the debate.

Mayor Gavin Newsom has been resolute in defending San Francisco's sanctuary status, and on Thursday his spokesman said Newsom supports Ammiano's idea for a card, which could be used for libraries, golf courses, public transportation and other services.

"The mayor strongly believes that this identification card should be extended to all San Franciscans, regardless of their immigration status," said Nathan Ballard, the mayor's spokesman.

The card also would be available to homeless people who prove they live in the city through a letter from a social service agency, Ammiano said. Currently, single-room-occupancy hotels require guests to leave an identification card at the front desk to enter the premises, which has been a burden on homeless visitors, Ammiano said.

Elderly people, youth and transgender people who face barriers to getting identification also would benefit from the card, he said.

New Haven began issuing the cards this summer. The application for the card is a simple form on which people can request that the information remain confidential. The card allows users access to the library and other public facilities and to put up to $150 on the card to pay for parking meters and for purchases at 50 stores in the city.

One immigrant-rights advocate said she had a "good feeling" about the cards becoming a reality in San Francisco.

"While they would not provide people permission to drive, and people aren't able to use them outside of San Francisco, they will really help undocumented immigrants ... with day-to-day functions," said Renee Saucedo, co-director of the San Francisco Day Labor Program, a project of La Raza Centra Legal.