President-elect Donald Trump has made no secret of his disdain for illegal aliens – especially those who commit crimes – and the sanctuary cities that protect them.

By most estimates, there are at least 800,000 criminal non-citizens moving about freely in the United States and at least that many more sitting in jails. Most are harbored in the nation's approximately 325 sanctuary cities.

Now the mayors of 30 sanctuary cities affiliated with the Cities for Action coalition have sent an open letter to President Obama pleading for him to grant protection from deportation to illegal aliens before he leaves office. The letter specifically asks for a two-year extension of the DACA program to some 740,000 participants, who are mostly young adults who came here illegally with their parents and are either enrolled in classes or working.

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The letter [see full text at end of article] said:

“We call upon your administration to accept early renewal applications for current DACA holders to extend temporary protections for them. In addition, we urge USCIS to commit to speedy processing of initial and renewal applications.”

The letter made a second appeal to the president:

“Second, we urge you to extend protections for immigrants who cannot return safely to their countries of origin because of extraordinary conditions, including natural disasters or armed conflict.”

The mayors also requested that President Obama protect the personal information of DACA participants, ostensibly to prevent Trump from using it if he decides to follow through on his deportation plans.

A sanctuary city is a designation that welcomes illegal immigrants, making it easier for them to get government services or avoid federal immigration agents.

These “safe havens” have come under fire since Kathryn Steinle was shot and killed in San Francisco by an illegal immigrant who had been deported five times. Other illegals sheltered from deportation by sanctuary cities have killed, raped and molested children.

The White House has not commented on whether or not Obama will use his final days in office to issue protection for illegal immigrants.

Chicago Mayor Rahm Emanuel, Los Angeles Mayor Eric Garcetti and New York City Mayor Bill de Blasio signed the letter along with mayors in Baltimore, Austin, Denver, Knoxville, Philadelphia, Seattle, Syracuse and other cities. They have all passed resolutions to keep their “sanctuary city” status.

Chicago had more than 50 shot and 12 killed over the weekend, bringing to a close one of its bloodiest years ever. The city finished out the year with 762 homicides, the highest number in nearly two decades. Despite Chicago's "sanctuary" status, it's possible one might be safer seeking sanctuary in Aleppo or Baghdad.

More cities scrambling to become sanctuaries

Locally elected officials in dozens of cities are scrambling to add their cities to the “sanctuary city” list. They believe strength in numbers will work against the Trump administration’s immigration enforcement.

A robocall regarding Iowa City, Iowa's, discussion on whether to become a sanctuary city sent a flood of calls into the city clerk's office last week.

Simon Andrew, the assistant to the city manager, said the calls started Wednesday afternoon with people reporting that an automated message had told them the City Council planned to vote on a sanctuary city status at its meeting on Jan. 3.

A recording of the call from Priorities for Iowa, however, shows the call only notifies residents of the discussion and does not mention a vote.

Mayor Jim Throgmorton told KCCI in Des Moines the council plans to discuss a sanctuary-city status Tuesday night. Throgmorton said the discussion had been prompted by an influx of requests from citizens since the November election for Iowa City to become a sanctuary city.

Officials in Howard County, Maryland, comprised of mostly Democrats, say they want to ban county officials from inquiring about an individuals’ immigration status. The officials would also be barred from cooperating with federal immigration officials, according to the Baltimore Sun.

“The recent national political climate, increased incidents of hate speech and violence, and unfortunate statements made by our nation’s president-elect, has caused many in the Howard County community to fear for their personal safety and the loss of civil liberties,” Howard County City Council member Calvin Ball said.

Jessica Vaughan of the Center for Immigration Studies told the Baltimore Sun she didn’t understand the purpose of the sanctuary city classification for Howard County, as it’s largely based in a drummed-up fear about federal immigration officials.

“I’m at a loss to see how this would affect the real life practices of Howard County officials or force them to do anything they’re already doing,” said Vaughan. “This idea that immigration officers are suddenly going to be raiding elementary schools and so county officials need to enact these policies to protect people from this activity is just silly. It doesn’t happen that way and it never will. This is a solution in search of a problem.”

Even very small cities, such as Langley, Washington, on Whidbey Island, are considering becoming sanctuaries for illegals.

“It’s an important issue to us and we’re considering it seriously and moving forward deliberately,” Callison told the South Whidbey Record. He said the issue could be voted on at the Jan. 17 council meeting.

Trump's 'switch' to turn off sanctuaries

Regardless of which side of the sanctuary issue one stands, no one is denying that a showdown is looming between the new president and sanctuary mayors.

Rep. John Culberson, R-Texas, says he has installed a policy "switch" within the Department of Justice that is ready to go on the first day of the Trump presidency, as WND reported.

All Trump has to do is flip the switch to activate a cut on all federal funds flowing into police and sheriffs' departments nationwide that aren't cooperating with federal immigration officers.

Some cities have promised to sue the federal government, but that won't help, Culberson said in an interview with Shannon Bream of Fox News.

“Suing will not do them any good. This is their decision. This is the law now, as a result of what I’ve done on July 7. If you want federal money, follow federal law,” he told Bream. “You must hand over every criminal illegal alien in your prisons to fed authorities to be deported immediately or you lose all your money.”

Read full letter from the 30 sanctuary cities below: