By JULIE HIRSCHFELD DAVIS and CHARLIE SAVAGE
WASHINGTON — The Trump administration, signaling its intent to toughen enforcement of immigration laws across the country, threatened on Monday to withhold or revoke law enforcement funding from states, cities and localities that block the police or sheriffs from telling federal authorities about undocumented immigrants in their custody.
In an announcement at the White House, Attorney General Jeff Sessions said state and local governments seeking certain law enforcement grants would have to certify that they were complying with a law that bars any official from withholding information from the Department of Homeland Security about a person’s immigration status. Those that are violating the policy could see such grants clawed back, he said.
Mr. Sessions’s appearance was an effort to threaten painful consequences for so-called sanctuary cities, those that decline to cooperate with the federal government in efforts to track and deport undocumented immigrants.
“I strongly urge our nation’s states and cities and counties to consider carefully the harm they are doing to their citizens by refusing to enforce our immigration laws and to rethink these policies,” Mr. Sessions said. “Such policies make their cities and states less safe — public safety as well as national security are at stake — and put them at risk of losing federal dollars.”
Mr. Sessions suggested the policy would apply to a total of $4.1 billion this year in various grants administered by the department.
Still, Mr. Sessions did not announce any new policy on Monday. His announcement appeared to be essentially a reiteration or reminder of the status quo. Last July, the Department of Justice under the Obama administration announced a policy of conditioning federal grants on compliance with a 1996 federal statute. The statute forbids imposing restrictions on the ability of the local police or sheriffs to exchange information with federal immigration authorities about the citizenship or immigration status of prisoners in their custody.
While the law does not require local law enforcement officials to turn over that information, it is aimed at discouraging efforts by cities or states to block such talks. The Obama-era announcement said it would give cities that were not in compliance with the law a reasonable period to adjust their policies, and it is not clear whether any grants have yet been blocked as a result.
July’s policy change came after a May report by the Justice Department’s Office of Inspector General that looked at the 1996 statute through the lens of local ordinances and rules in 10 major cities, finding that many limited the information local authorities could provide to federal immigration agents.
For example, the report cites a 2014 law in New York City that restricts the corrections department from telling Immigration and Customs Enforcement officials about an inmate’s release date, incarceration status or coming court dates unless the inmate was the subject of a detainer request supported by a judicial warrant. As a result, the report said, ICE closed its office on Rikers Island.
New York received about $53 million — a tiny fraction of its budget — from the Justice Department in the most recent fiscal year, according to City Hall officials. Much of that funding goes to the police and corrections departments for the police crime lab; ballistic helmets and vests for officers; crime prevention programs; drug and gang task forces; and the like.
Mayor Bill de Blasio said in a statement that the “latest threat” from the Trump administration “changes nothing” in New York. “Any attempt to cut N.Y.P.D. funding for the nation’s top terror target will be aggressively fought in court,” he said.
While Mr. Sessions acknowledged on Monday that what he was discussing was essentially a continuation of the Obama-era policy, he suggested that it could be a first step to imposing more stringent requirements on federal money in the future.
“We believe that grants in the future could be issued that have additional requirements, as every grant that’s being issued in America today usually has requirements that if you qualify for this grant, you have to meet certain requirements,” he said. “So we’ll be looking at that in the future, and we’ll continue to pursue it.”
Immigrant advocacy groups, civil rights organizations and Democrats sharply denounced Mr. Trump’s latest effort to highlight his tough stance. Tom Perez, the chairman of the Democratic National Committee, called the announcement an effort to “bully” immigrant families.
“It’s simply outrageous that the Trump administration and their ICE agents are putting politics and scapegoating of immigrants ahead of public safety and the ability of local communities to decide how best to keep their communities safe,” said Frank Sharry, the executive director of America’s Voice Education Fund.
Eric T. Schneiderman, the New York attorney general, called Mr. Trump’s approach “draconian.”
“Despite what Attorney General Sessions implied this afternoon, state and local governments and law enforcement have broad authority under the Constitution to not participate in federal immigration enforcement,” he said.
The Trump administration has repeatedly signaled its intention to carry out an immigration crackdown. One of Mr. Trump’s first actions when he became president was signing an executive order that included an attempt to lay the groundwork for building a wall along the Mexican border and to encourage more agreements delegating to state and local law enforcement agencies the ability to enforce federal immigration laws.