The immigration enforcement raids that have occurred in cities across the country have largely been absent in Louisville, Ky. Federal funds, which have been choked off to some municipalities, have continued to flow to the city. There has been no talk of deploying National Guard troops to neighborhood streets, as in Los Angeles and Washington, D.C.

Mayor Craig Greenberg of Louisville, elected to lead a blue city in a deep-red state, is trying to keep it that way with a rare gambit for a Democratic mayor. He has agreed to the Trump administration’s request to place a 48-hour hold on immigrant inmates at the city’s jail that would allow the Department of Homeland Security more time to detain them.

The new policy, a reversal of a 2017 city ordinance that limited how the police could work with immigration authorities, seems to have achieved the mayor’s goal for now. Louisville was removed this month from the Department of Justice’s list of sanctuary cities, counties and states that are being threatened with litigation.

But the mayor’s decision has also generated blowback from Democratic leaders and immigrant rights organizations in a city with a rich history of opening its arms to refugees and where Kentucky’s two headlining industries — horse racing and bourbon — rely heavily on labor from immigrants, including many who are undocumented.

Since the early 1990s, resettlement programs have helped make Louisville a landing spot for immigrants fleeing wars in Bosnia and central Africa, and economic hardships in Cuba and Haiti. Louisville, with a population of roughly 640,000, has more Cuban immigrants than any other U.S. city outside Miami. More recently, Central Americans have landed in Louisville.

The city estimates there are nearly 80,000 immigrants in the metro area, about half of whom are naturalized.

In announcing the policy change last month, Mr. Greenberg said he agreed to the request to prevent a widespread federal crackdown. “I will not risk the safety of our broader immigrant community,” he said.

While critics acknowledge that Mr. Greenberg was in a difficult position, they say that agreeing to the administration’s demands offers no guarantee that immigration raids will be tempered and federal funds won’t be cut off.

The move also raises the question of whether this will affect his political fortunes. In Louisville, he won in a crowded Democratic primary field by nearly 20 percentage points in 2022 and won the general election by five percentage points.

“Any day that we allow the administration to bully us is not a good day,” said Nima Kulkarni, a state representative who represents the area around the Churchill Downs horse racing track and is an immigration lawyer.

Pam Bondi, the U.S. attorney general, has celebrated Mr. Greenberg’s decision. “This should set an example to other cities,” she wrote on social media. “Instead of forcing us to sue you — which we will, without hesitation — follow the law, get rid of sanctuary policies, and work with us to fix the illegal immigration crisis.”

But not all Democratic mayors are in the same spot. Some, as in Atlanta and Cleveland, do not have jurisdiction over the city jail. In New York, Mayor Eric Adams tried to allow U.S. Immigration and Customs Enforcement agents into the city’s Rikers Island jail, but a state judge indefinitely blocked his executive order after the City Council sued in opposition. The mayor’s attempt to help the Trump administration did not stop the Department of Justice from suing the city.

Many Democratic mayors find themselves in positions similar to those who head law firms, universities and agencies that have promoted diversity initiatives. They face a multipronged attack from the federal government, which plays a sizable role in a city’s well-being through funding and policy.

“It’s political blackmail,” said Mayor Aftab Pureval of Cincinnati, another red-state city run by a Democrat. “Every mayor in the country wants to follow the law, but we’re in a country led by Trump where it’s not about following the law, it’s about following the politics. If you don’t follow his politics, the threat of removing federal funding is an existential threat.”

Mr. Pureval, like other mayors who were interviewed, did not criticize Mr. Greenberg but added that “the fundamental question we all face is: When does protecting your constituents go from trying to avoid confrontation to confrontation?”

Kentucky Republicans have largely applauded the new policy, which puts Louisville into alignment with the commonwealth’s other cities. “Today is a victory for every Kentuckian and the rule of law,” Daniel Cameron, the former Kentucky attorney general and current Senate candidate, wrote on social media when the decision was announced.

Mr. Greenberg declined to be interviewed, but in his public remarks, he affirmed his commitment to Louisville’s immigrant community. Shortly after taking office in 2023, he created the Office of Immigrant Affairs, which coordinates a free leadership training program for foreign-born residents.

But leaders of support organizations in the city were irked that the mayor indicated in his public remarks that he had consulted them before reaching his decision. In reality, the mayor simply declared his plans and did not seek advice, according to two people who met with Mr. Greenberg who spoke on condition of anonymity for fear of retribution. A spokesman for the mayor did not respond to a request to comment on the characterization of the meeting.

The mayor met again with community leaders last week.

Mr. Greenberg has said there are about 100 inmates annually in the Louisville jail who are subject to detainers, requests by federal officials to be notified of a release. As of last Monday, just after the 48-hour holds went into effect, the mayor’s office said 36 people were being held in the jail who were subject to detainers.

Louisville had been holding immigrant detainees for five to 12 hours, according to the mayor. While every state has seen an increase in immigration arrests since President Trump took office, Kentucky has experienced the smallest bump (28 percent), according to data reviewed by The New York Times. There are rarely more than 10 immigration arrests per day in the state.

Some expect those numbers to climb as D.H.S. uses the lure of a $50,000 signing bonus to recruit new ICE officers in a state as poor as Kentucky. ICE did not respond to a request for comment.

Some immigrants in the city who were interviewed said they were disappointed in the mayor’s decision. An owner of a Louisville restaurant, who came to the United States as a teenager and said he was in the process of trying to gain legal residency, said the new policy made him feel as if people like him were unwelcome. But the man, who spoke on the condition of anonymity because he is undocumented and concerned about drawing attention from federal authorities, said he was trying to stay hopeful.

The influx of immigrants in the city has spawned a network of organizations that provide services including English classes, day care and legal aid. On a recent morning, the reception area of one immigrant services agency was packed with people speaking Spanish, Arabic, Haitian Creole and Portuguese.

But concern remains among immigrant support groups that Louisville will still be a target for a federal raid.

Carla Wallace, the co-coordinator of the support group Louisville Showing Up for Racial Justice, said the organization had 200 trained volunteers who could alert others if they see signs of federal raids and could help provide services to people who are afraid they will be apprehended on the streets. The volunteers have escorted a group of Latino children on an outing to the zoo and have delivered groceries to families who are afraid to go food shopping.

“The fear is huge,” she said.

Albert Sun contributed reporting.