Immigrants living in the District illegally may soon be able to apply for a driver’s license indistinguishable from those issued to legal residents, following D.C. Council action Tuesday.

A council committee voted unanimously to modify a proposal from Mayor Vincent C. Gray (D) that would allow residents living in the District illegally to secure local identification and driving rights for the first time. Under Gray’s version of the legislation, applicants who could not prove their citizenship would have their identification cards marked as “not acceptable by federal agencies for official purposes.”

That provision was intended to comply with a federal law, the REAL ID Act, that requires localities to verify the “lawful status” of people issued driver’s licenses or identification cards. Without it, Gray administration officials fear, District licenses might become invalid for federal purposes ranging from boarding airline flights to applying for Social Security benefits.

Immigrant advocates and their backers on the council argued that distinguishing between immigrant and non-immigrant licenses would effectively mark holders of the former as illegal. “It’s like a scarlet letter on undocumented residents,” said Chairman Phil Mendelson (D).

They turned Gray’s “one city” campaign slogan into a rallying cry, calling for “one city, one license,” and the council’s Transportation and Environment committee agreed, saying a dual-license provision “may lead to significant harm” to immigrants holding marked identification.

Mary M. Cheh (D-Ward 3), the panel’s chair, initially questioned the notion that there should be a single license. But a report authored by her committee concluded that “the potential harm to the District’s undocumented residents outweighs the requirement that the District comply with REAL ID” — a law, the report noted, that remains unenforced and is “rife with controversy, unfunded mandates, unrealistic and moving deadlines, and privacy issues.”

“I had to be convinced that there was a way to steer our way through this, and we figured it out,” Cheh said, who said the bill is not intended as an defiant act toward the federal government.

If the Department of Homeland Security begins enforcing the ID law, “we can worry about that when the time comes,” she said. “Giving immediate relief to people who are undocumented and giving them a license, and the safety that will give us, takes precedence.”

Pedro Ribeiro, a spokesman for Gray, said the mayor stands by his original bill and suggested that the change could “open up a Pandora’s box” of consequences — including possibly leaving District driver’s licenses invalid at airport security checkpoints.

Under the committee’s bill, a person who cannot prove his or her lawful presence in the country could apply for a D.C. driver’s license or identification card after living in the District for at least six months, obtaining a tax identification number from the Internal Revenue Service and providing a valid foreign passport or birth certificate.

Jim Graham (D-Ward 1), who said he feared the potential for sharing information between the IRS and immigration authorities, sought unsuccessfully to amend the bill to remove the tax-number requirement. “We’ve got to resist the entanglement of these federal processes in our local driver’s licenses,” he argued.

Nine states, including Maryland, have passed laws allowing immigrants living there illegally to secure driver’s licenses. Two of them, New Mexico and Washington state, do not differentiate the immigrants’ licenses.