President-elect Donald Trump’s choice to carry out his sweeping deportation plans may operate with more power and less congressional oversight than some of his own Cabinet members.

That’s because the appointee, former acting director of U.S. Immigration and Customs Enforcement, Tom Homan, will not be directly in charge of the Department of Homeland Security or any subagency charged with addressing immigration issues.

Homan will instead be the Trump administration’s “Border Czar,” a title that could give him significant influence over immigration and border policy without the formal authority — and guardrails — that come with being Cabinet secretary.

Trump announced Homan’s selection in a post on his Sunday evening Truth social platform, putting the immigration hardliner “in charge of our nation’s borders.”

Homan will also “be in charge of all deportations of illegal aliens back to their countries of origin,” Trump wrote in the post.

Unlike Cabinet nominees — or the roughly 1,200 other federal positions that require Senate confirmation — Homan does not need congressional approval to serve under Trump. And he could be isolated from other forms of legislative oversight, experts told CNBC.

“White House appointees are subject to less oversight than Cabinet and sub-Cabinet officials,” said Katherine Hawkins, senior legal analyst for the Project on Government Oversight.

“It is much more difficult for Congress to enforce subpoenas against White House officials, and it is more likely that they will invoke executive privilege and refuse to testify and that refusal will be upheld in court,” Hawkins said.

These staffers may lack formal authorization from Congress, but that does not necessarily mean they are subordinate to their Senate-confirmed counterparts.

“Who is actually more powerful in practice depends on things like access to the president and the willingness of the Cabinet and other officials to refuse the White House’s demands,” Hawkins said.

A spokesperson for the Trump transition declined CNBC’s request for comment.

Lee Gelernt, an attorney with the American Civil Liberties Union who helped challenge immigration policy during the Trump and Biden administrations, agrees.

Homan’s lack of an agency position “will not diminish his influence and may make it more difficult to implement meaningful checks on his actions,” he said.

Faisal Al-Juburi, head of external affairs at the immigrant rights group RAICES, said czars can have major policy impact “while at the same time hampering congressional oversight, which is critical to ensuring the accountability of those acting on behalf of the US government. ”

The messages “create opaque conditions that make it difficult, if not impossible, to determine who has authority over policies that could have a broad impact on the American people,” Al-Juburi said.

On the face of it, Trump’s post gives Homan an enormous amount of power.

When the new administration takes power on January 20, 2025, Homan will be responsible for carrying out what was a central promise of Trump’s presidential campaign: deporting millions of undocumented immigrants.

Homan’s scope includes, but is not limited to, the southern border, the northern border, all maritime and aviation security, Trump wrote.

Implementing a mass deportation plan would pose unprecedented logistical challenges and require complex, large-scale collaboration among federal government agencies, local law enforcement resources, host countries, and other entities. The process of locating, detaining and removing so many people, including mixed-status families and children, would be fraught and the costs would be astronomically high, NBC News reports.

Homan, 62, has been one of the policy’s loudest advocates. A regular guest on Fox News and a speaker at the 2024 Republican National Convention, he reportedly vowed earlier this year to lead “the largest deportation force this country has ever seen.”

Homan has been called the father of the Trump administration’s highly controversial “zero tolerance” border policy, which resulted in the separation of thousands of immigrant families and was reversed by Trump in 2018.

When asked in a recent interview with CBS News’ “60 Minutes” whether mass deportations could happen without family separation, Homan said, “Of course it does.” Families can be deported together.”

Gelernt said that given Homan’s actions during Trump’s first administration and his subsequent statements, he expects the appointment “will have far-reaching anti-asylum and anti-immigrant implications.”

It is unclear how Homan will be able to exercise his power. “It is extremely doubtful that any member of the White House staff, the kind of person sometimes called a czar, can actually exercise legal authority,” professor John Harrison of the University of Virginia School of Law told Congress in 2009.

But “in practice” these staffers can still exert significant influence on policy decisions, Harrison told CNBC in an interview Monday.

Hawkins pointed to Trump’s senior policy aide Stephen Miller, saying he was “probably the most influential policy voice on immigration and border issues” during the Republican’s first term in the White House.

“DHS officials have backed off to some extent,” she said, “but Miller lasted the longest and was closest to Trump and usually got his way.”

Miller is expected to be appointed as Trump’s deputy chief of staff for policy, NBC reported Monday.