Former Immigration and Customs Enforcement Director Tom Homan will become the “border czar” in the Trump administration, President-elect Donald Trump announced on Truth Social.

Homan, a staunch Trump supporter, will lead the mass deportations Trump promised during his 2024 campaign.

“I have known Tom for a long time, and there is no one better at guarding and controlling our borders,” Trump wrote in his post on Sunday evening.

“Similarly, Tom Homan will be in charge of all deportations of illegal aliens back to their countries of origin. Congratulations to Tom. I have no doubt he will do a fantastic, and long overdue, job,” Trump added.

Homan oversaw ICE during the Trump administration’s “zero tolerance” enforcement of parents being separated from their children at the border.

The American Civil Liberties Union (ACLU) estimates that there are somewhere between 500 and 1,000 families who have not been reunited.

In August, ACLU attorney Lee Gelernt told ABC News it’s impossible to know an exact number because they haven’t found them all.

During an interview on “60 Minutes” in October, Homan said future family separations should be taken into account, but he also said “families could be deported together.”

With immigration a top issue for voters, Trump has said he is committed to rounding up and deporting millions of migrants living in the US without legal permission.

He reiterated a campaign promise to carry out mass deportations on “Day 1” at his rally at Madison Square Garden in New York City in October.

“On Day 1, I will launch the largest deportation program in American history to get the criminals out,” he said. “I will save every city and town that has been invaded and conquered, and we will put these vile and bloodthirsty criminals in jail and then kick them out of our country as quickly as possible.”

To do this, the former president said he would use local law enforcement and the National Guard to find migrants in the US

Trump has railed against the Biden administration’s immigration policies, claiming in part that it has made America less safe, even though statistics show that US-born citizens are more than twice as likely to be arrested for violent crimes than immigrants without papers.

An estimated 11 million people live in this country without legal immigration status.

If feasible, the cost of deporting even 1 million undocumented immigrants per year would cost more than $88 billion, for a total of $967.9 billion over more than a decade, according to a report from the American Immigration Council.

Armando Tonatiuh Torres-García and Meredith Deliso of ABC News contributed to this report.