• President-elect Donald Trump picked immigration hard-liner Tom Homan as his "Border Czar."
• Homan, the former acting director of U.S. Immigration and Customs Enforcement, has advocated for mass deportations of undocumented immigrants.
• Homan will not need congressional approval to serve under Trump, and he may be insulated from other forms of legislative branch scrutiny, experts told CNBC.

President-elect Donald Trump's pick to carry out his sweeping deportation plans may be able to operate with more power, and less oversight from Congress, than some of his own Cabinet members.

That's because the appointee, former U.S. Immigration and Customs Enforcement acting Director Tom Homan, will not be put directly in charge of the Department of Homeland Security or a subagency tasked with addressing immigration issues.

Homan will instead be the Trump administration's "border czar," a title that could grant him significant influence over immigration and border policy without the formal authority — and guardrails — that come with being a Cabinet secretary.

Trump announced Homan's selection in a Sunday night post on his Truth Social platform, putting the immigration hard-liner "in charge of our Nation's Borders."

Homan will also "be in charge of all Deportation of Illegal Aliens back to their Country of Origin," Trump wrote in the post.

Unlike Cabinet nominees — or the roughly 1,200 other federal roles that require Senate confirmation — Homan will not need congressional approval to serve under Trump. And he may be insulated from other forms of legislative branch scrutiny, experts told CNBC.

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

"It is much harder for Congress to enforce subpoenas against White House officials, and they are more likely to cite executive privilege and refuse to testify and have that refusal upheld by courts," Hawkins said.

Those staffers may lack the formal authorization of 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 Cabinet and other agency officials' willingness to refuse White House 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 has helped challenge immigration policies during the Trump and Biden administrations, agreed.

Homan's lack of an agency position "will not decrease his influence and may make it harder to have meaningful checks on his actions," he said.

Faisal Al-Juburi, chief external affairs officer of the immigrant rights advocacy group RAICES, said czars can make major policy impacts "while simultaneously obstructing congressional oversight, which is critical to ensuring accountability of those acting on behalf of the U.S. government."

The posts "create opaque circumstances that make it difficult, if not impossible, to determine who maintains authority over policies that stand to have a wide-ranging impact on the American people," Al-Juburi said.

Leading the charge

Taken at face value, Trump's post gives Homan a massive amount of power.

When the new administration takes control on Jan. 20, 2025, Homan will be in charge of implementing what was a central promise of Trump's presidential campaign: deporting millions of undocumented immigrants.

Homan's purview includes, but is "not limited to, the Southern Border, the Northern Border, all Maritime, and Aviation Security," Trump wrote.

Carrying out a mass deportation plan would involve unprecedented logistical challenges and require intricate, large-scale cooperation between federal government agencies, local law enforcement sources, host nations and other entities. The process of locating, detaining and removing that many people, including mixed-status families with children, would be fraught, and the costs would be astronomical, NBC News has reported.

Homan, 62, has been one of the loudest supporters of the policy. A regular on Fox News and a speaker at the 2024 Republican National Convention, he reportedly vowed earlier this year to "run the biggest 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' "60 Minutes," whether mass deportations could happen without family separation, Homan said: "Of course there is. 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, anti-immigrant implications."

How Homan will be able to wield his power is unclear. "It is extremely doubtful whether anyone on the White House staff, the sort of person sometimes called a czar, could actually exercise legal authority," professor John Harrison of the University of Virginia School of Law told Congress in 2009.

But "as a practical matter," those staffers can still wield significant influence over policy decisions, Harrison told CNBC in an interview Monday.

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

"DHS officials pushed back 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 tapped as Trump's deputy chief of staff for policy, NBC reported Monday.