Attorney General Jeff Sessions. Associated Press/Andrew Harnik

Attorney General Jeff Sessions accused city officials in Chicago on Monday of obstructing federal immigration laws "to a degree perhaps unsurpassed by any other jurisdiction" after the city sued the Trump administration over its threat to cut off federal grants to so-called sanctuary cities.

"No amount of federal taxpayer dollars will help a city that refuses to help its own residents," Sessions said in a statement. "This is astounding given the unprecedented crime surge in Chicago, with the number of murders in 2016 surpassing both New York and Los Angeles combined."

Sessions last month toughened the Department of Justice's crackdown on sanctuary cities, or cities that limit cooperation with federal immigration authorities. He announced that certain grant programs for cities and states would be awarded only to jurisdictions that allow federal immigration officers into detention facilities and provide 48 hours' notice before releasing inmates wanted by federal authorities.

The move was a significant escalation in the Trump administration's approach to sanctuary jurisdictions, which typically refuse to honor federal requests to detain immigrants in jails past their scheduled release dates unless the requests are accompanied by a warrant from a judge.

Chicago, among other jurisdictions, reacted with hostility to the new measures, saying they would infringe upon the independence of local law-enforcement agencies and undermine the inroads police officers have made in gaining trust from immigrant communities fearful that encounters with the local police will lead to deportations.

At stake for Chicago is roughly $2.3 million from the Edward Byrne Memorial Justice Assistance Grant. That pales in comparison to Chicago's $9.8 billion budget, but Chicago officials have argued that more grants are likely to be at risk if the Trump administration is permitted to make such funding conditional upon cooperation with immigration authorities.

Mayor Rahm Emanuel of Chicago on March 28, 2016, announcing the appointment of Eddie Johnson, right, as the interim superintendent of the Chicago Police Department. Reuters/Kamil Krzaczynski

In Chicago's lawsuit, the city argues that such conditions "fly in the face of longstanding City policy that promotes cooperation between local law enforcement and immigrant communities."

"Chicago will not let our police officers become political pawns in a debate," Mayor Rahm Emanuel said at a news conference announcing the lawsuit. "Chicago will not let our residents have their fundamental rights isolated and violated. And Chicago will never relinquish our status as a welcoming city."

Yet Sessions on Monday cited Chicago's soaring murder rate as evidence that the city was mismanaging its approach to crime control. It's not the first time the Trump administration has singled out Chicago in its efforts to crack down on violent crime — President Donald Trump has vowed multiple times to "send in the feds" if the city cannot reduce the violence on its own.

"The mayor complains that the federal government's focus on enforcing the law would require a 'reordering of law enforcement practice in Chicago,'" Sessions said. "But that's just what Chicago needs: a recommitment to the rule of law and to policies that roll back the culture of lawlessness that has beset the city."

Chicago is far from the only city to turn to litigation over the Trump administration's immigration policies. In April, San Francisco and Santa Clara County won an injunction against an executive order denying certain federal funds to "sanctuary cities."