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.