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Attorney General Jeff Sessions slammed Chicago on Wednesday, dubbing it and other so-called “sanctuary cities” “a trafficker, smuggler, or predator’s best friend,” and continued threatening it with the loss of federal crime-fighting funds.

“Respect for the rule of law has broken down. In Chicago, their so-called ‘sanctuary’ policies are just one sad example,” Sessions said at speech in Miami, where he was touting that city’s cooperation with federal immigration authorities.

“Chicago’s leaders have made this a political issue and direct their police to refuse” requests from federal immigration officials, he said.

“This is a serious problem for the people of Chicago,” added Sessions, who also implored Windy City residents to reach out to their local leaders.

“If voters in Chicago are concerned about losing federal grant money, call your mayor,” he said.

Chicago Mayor Rahm Emanuel quickly hit back, saying in a statement to NBC News that his city would "not cave to the Trump administration’s pressure because they are wrong morally, wrong factually and wrong legally."

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“In a week in which the Trump administration is being forced to answer questions about neo-Nazis, white supremacists, and the KKK, they could not have picked a worse time to resume their attack on the immigrants who see America as a beacon of hope,” Emanuel added.

U.S. Conference of Mayors Executive Director Tom Cochran also retaliated, saying that Sessions "doesn’t understand what it means to run a city that welcomes immigrants" or "the Constitutional protections afforded to all people in our country and their impact on local policies."

“The U.S. Conference of Mayors stands with Chicago Mayor Rahm Emanuel and deplores the attacks which the Attorney General leveled against him today and on previous days. An assault on one mayor is an assault on all mayors," Cochran said.

Sessions, in his speech, had been referring to new rules he introduced last month under which sanctuary cities ─ municipalities that have refused to cooperate in the administration's attempt to round up and report more undocumented immigrants ─ stand to lose millions in future federal grant money if they don't help federal agents deport suspected undocumented immigrants held in local jails.

The measure — just the latest step the Trump administration has taken as part of its aggressive stance against sanctuary cities — prompted the city of Chicago to file a lawsuit accusing the Justice Department of forcing it to police undocumented immigrants in a way that would violate people's' rights, damage public trust and make the city less safe.

“If Chicago submits to the Department’s demands, it will forfeit decades’ worth of trust and goodwill that its police force has built in the communities it serves," the city alleged in the lawsuit. "And as those decades of experience show, that kind of trust, once lost, is lost forever."

Emanuel, added in his own statement after the suit was filed that he refused to be "blackmailed" into choosing "between our values and our Police Department’s philosophy of community policing.”

Trump and Sessions have been particularly outspoken about crime in Chicago — which has more murders this year than New York and Los Angeles combined — with the president frequently blasting the city over its high crime rates and threatening to "send in the feds.”

Emanuel, in turn, has taken a leading role in the resistance to Trump's crackdown on so-called "sanctuary cities

He’s not the only one.

Officials in several cities, including Chicago, San Francisco and New York, have said they are prepared to file suit against the Trump administration.

In addition, in April, a federal judge in California blocked the Trump administration from withholding current grant money from cities that resist cooperation with ICE.