Former NYPD Chief Bill Bratton on bid former President Trump "good luck" regarding the former president's pledge to expel millions of migrants in the largest deportation program in American history.

"Former President Trump is talking about deporting 10 million to 15 million people. Good luck with that one … I spent enough time in Latin America consulting and understand the desperation [of the] that people are fleeing [from] those countries. They want to work … They are part of that underground economy," Bratton said on "Catsimatidis Roundtable Show" on Sunday.

"But the idea of getting rid of 10 million or 15 million people, I don’t think Mr. Trump is doing himself a favor or the Republican Party by raising that," he added.

Trump has kept immigration at the forefront of his campaign to take back the White House in November.

Trump, when pressed for specifics on his plan in an interview with Time Magazine this year, suggested he would use the National Guard, and possibly even the military, to target between 15 million and 20 million people. The government estimated in 2022 there were 11 million migrants living in the U.S. without permanent legal permission.

A recent Scripps News/Ipsos survey found that more than half of all Americans, including a quarter of Democrats, support the mass deportation of immigrants who are living in the country illegally.

About 54 percent of respondents — 86 percent of Republicans, 58 percent of independents and 25 percent of Democrats — said they “strongly” or “somewhat” support a wide-scale effort to deport millions of immigrants, and 59 percent said they are closely following the “immigration situation at the U.S.-Mexico border.”

The survey also found that 39 percent of respondents named immigration a top issue for them this election year — second only to inflation.

The Associated Press contributed.