The man that President-elect Donald Trump has tapped to be his border czar, Tom Homan, has made a bombshell promise in a massive blue city.

He was on hand in Chicago, a city whose mayor has vowed to fight the Trump administration on its deportation plans, where he said he would start on “day one.”

He gave the comments on Monday at a Christmas party hosted by the Northwest Side GOP, WFLD-TV reported.

“All that starts January 21st, and we’re going to start right here in Chicago, Illinois,” he said.

“If your Chicago mayor doesn’t want to help, he can step aside. But if he impedes us — if he knowingly harbors or conceals an illegal alien — I will prosecute him,” he said in a stern warning to Democrat Mayor Brandon Johnson.

He also took a swipe at the state’s Democrat Gov. JB Pritzker in his speech.

“Chicago is in trouble because your mayor sucks and your governor sucks,” he said.

“January 21st, you’re going to look for a lot of ICE agents in your city, looking for criminals and gang members,” he said, indicating that the deportations would start the day after the inauguration of the president-elect.

The governor’s office responded to the comments with blistering words.

“It’s no secret that Illinois will face countless, baseless attacks over the next four years from the Trump Administration. Rather than responding to every ridiculous boast from Trump lackeys, Governor Pritzker is focused on what he was focused on during the first Trump term: leading our state with competence instead of chaos,” it said.

In a segment in November, CNN host Kasie Hunt interviewed Homan and played two video clips — one of Denver Mayor Mike Johnston, who has promised to obstruct czar Tom Homan’s efforts to apprehend illegal immigrants. Johnston made headlines earlier for suggesting that he would like to see city police block federal immigration authorities from entering Denver, an action he compared to Tiananmen Square.

Hunt then played a clip of Homan during a Fox News segment with host Sean Hannity, where he promised that Johnston and other obstinant Democratic officials would face legal repercussions if he followed through on his threat to block federal immigration authorities.

“But look, me and the Denver mayor we agree on one thing. He’s willing to go to jail. I’m willing to put him in jail. There’s a statute, Title 8, United States Code 1324 – AAA. And what it says is it’s a felony if you knowingly harbor and conceal illegal aliens from immigration authorities. It is also a felony to impede a federal law enforcement officer,” Homan.

“So if you don’t want to help, that’s fine. He can get the hell out of the way, but we’re going to go do the job. President Trump has a mandate from the American people. We’ve got to secure this country and save American lives,” he added.

That led Hunt to react with a stunned “Ooof!”

Earlier in November, Boston’s Democratic Mayor Michelle Wu faced scrutiny after vowing to deny federal authorities access to city resources during raids aimed at locating and arresting violent criminals.

While a 2014 city ordinance prevents cooperation on civil immigration matters, it does not apply to criminal cases, according to the Boston Herald. Wu told a local TV station, “We are not cooperating with those efforts that actually threaten the safety of everyone by causing widespread fear and having large-scale economic impact.”

Homan further elaborated on the duties Trump has entrusted him with during his interview with Hannity.

“I find it shocking that any mayor of a city would say — President Trump’s been clear. We want to concentrate on public safety threats and national security threats,” he said.

“I find it hard to believe that any mayor or governor would say they don’t want public safety threats removed from their neighborhoods. I mean, I don’t know what the hell is going on in Denver, but we’re going to go and we’re going to fix it. If you don’t want to fix it, if he doesn’t want to protect his communities, President Trump and ICE will,” he continued.

That led Hannity to ask: “So you will be going into Colorado, Illinois, New York, California, and you are going to you are going to uphold the law of the land. That’s your commitment. It doesn’t matter what these elected politicians threaten or say that they are going to do?”

Homan was adamant: “We’re going to enforce the law, period, and they’re not going to stop us.”