When Mayor Kenney committed to launching a municipal ID program, he argued that having a photo identification card would improve the lives of undocumented immigrants living in the shadows.

A year later, his plans are on hold amid concerns that the program could actually put undocumented immigrants at risk.

The unease stems from an ongoing fight in New York over the applications of nearly a million people issued municipal ID cards in the last two years. A judge recently blocked Mayor Bill de Blasio's attempts to destroy the personal information on those applications. A bill introduced to the state Senate goes one step further, requiring the city to hand over the information to the U.S. Department of Homeland Security.

Philadelphia officials are watching cautiously.

"Municipal IDs are an excellent idea," said Philadelphia Office of Immigrant Affairs Director Miriam Enriquez, part of a team that has been studying the concept for more than a year. "But I think we have a responsibility to the communities that would benefit from a municipal ID, before we move forward in launching any program, to make sure anyone that would use that ID is also protected."

Municipal ID cards are meant to increase access to essential services for those who do not have a driver's license. The nation's first was launched in New Haven, Conn., in 2007, and programs are either active or in the process of being launched in San Francisco, Chicago, Detroit, Baltimore, and other cities.

To receive a card, applicants in general must provide documents to prove both their identity (such as a passport, marriage certificate, foreign national identity card, or birth certificate) and residency (such as a utility bill, lease, or letter from a homeless shelter stating that an applicant has recently stayed there).

In some cities, the cards can be used to enter city buildings or schools, file a police report, or even open a bank account. While undocumented immigrants would benefit, advocates also see a clear use for the homeless, those leaving incarceration, and transgender people.

In New York, the cards have gained even wider popularity, with nearly a million now in circulation, in part because they also provide a one-year membership at 40 cultural institutions and discounts at movie theaters, sporting venues, health clubs, and sporting venues.

Kenney has been a longtime supporter of the idea, first cosponsoring legislation to create a municipal ID program here in 2013. That bill stalled. In his first budget address as mayor, Kenney listed municipal ID as a key priority for 2016.

The programs have always faced controversy. Some critics see the cards as a stealth path to legal status for undocumented immigrants. Even some immigration advocates have opposed the efforts. The New York Civil Liberties Union did not endorse the municipal ID card there, saying the city had not done enough to protect application documents from being used by law enforcement.

That issue is now being tested.

In December, de Blasio's office announced that going forward, the city would no longer keep copies of applicants' identity or residency documents once a card is issued. The city also moved to destroy its copies of those documents for those who had already received cards, which the law creating the program allowed to happen before Dec. 31.

Two Republican members of the state Assembly filed suit to block the data from being destroyed, and a judge temporarily halted the city's plans. The judge has yet to make a final determination.

Separately, a Republican member of the state Senate last month introduced legislation that would require that a copy of the records be maintained by the state's Office for New Americans and Division of Homeland Security.

The bill would likely meet resistance in the Democratic-controlled Assembly.

In Pennsylvania, Republicans in both the House and Senate have shown an appetite for tough-on-immigration measures, including a bill that would strip state funding from Philadelphia because of its policy of not cooperating with federal immigration officials.

Enriquez stressed that the Mayor's Office still wants to see municipal ID become a reality. But she said she took both the local and national political climate into consideration when weighing whether this is the right time.

"All the executive orders, the travel ban, the sanctuary cities, building the wall," she said. "Memos are coming out left and right about immigration enforcement priorities."

Manuel Portillo, director of community engagement at the Welcoming Center for New Pennsylvanians, also questioned moving forward with the initiative. He said that even if Philadelphia can ensure that data remain confidential, immigrants who are living in fear are unlikely to apply.

"The fear factor is still going to be there," he said. "And it will be hard to convince people this is a good thing to do."

Others are less willing to see progress stymied by politics.

Councilwoman Maria Quiñones-Sánchez, who cosponsored the municipal ID legislation with Kenney in 2013 and sponsored similar legislation last year, said her position has always been that the city should not maintain a record of personal information once a person's identity is verified and a card is issued.

She said the current landscape only increases her desire to move forward quickly.

"This is the time when people need to feel embraced," she said. "This is the right time."

Sundrop Carter, executive director of the Pennsylvania Immigration and Citizenship Coalition, said concerns about data privacy should be taken seriously and addressed but not become roadblocks.

"I don't think politics should hold us back," she said. "Otherwise we're going to have four years of being in hiding."