Homeland Security Secretary Alejandro Mayorkas
CNN  — 

The Department of Homeland Security is bringing on a private law firm to help with potential impeachment proceedings against Secretary Alejandro Mayorkas, according to three sources familiar with the matter.

House Republicans have been moving to build a case against Mayorkas as they consider launching rare impeachment proceedings against a Cabinet secretary.

“The Department of Homeland Security has retained outside counsel to help ensure the Department’s vital mission is not interrupted by the unprecedented, unjustified, and partisan impeachment efforts by some Members of Congress, who have already taken steps to initiate proceedings,” a Homeland Security spokesperson said.

“DHS will continue prioritizing its work to protect our country from terrorism, respond to natural disasters, and secure our borders while responding appropriately to the over 70 Congressional committees and subcommittees that have oversight of DHS,” the spokesperson said.

The law firm is Debevoise & Plimpton, according to one source. While the Department of Homeland Security Office of General Counsel has various lawyers to deal with matters, including immigration and cybersecurity, the outside firm is being brought in on a government contract and only be utilized to the extent it is needed throughout the process, another source said.

Debevoise & Plimpton declined to comment.

It’s exceedingly rare for a Cabinet secretary to be impeached, something that has only happened once in US history – when William Belknap, the secretary of war, was impeached by the House before being acquitted by the Senate in 1876.

Republican lawmakers have argued that Mayorkas’ claims of having operational control of the border are unfounded and that the record arrests mark a dereliction of duty – two themes that have come up repeatedly in congressional hearings and have been cited as reason to impeach the DHS secretary.

Over recent weeks, key committee chairman already held two congressional hearings over the Biden administration’s handling of the US-Mexico border. Earlier this month, the House Judiciary Committee, which would have jurisdiction over an impeachment resolution, held its first border-related hearing.

“These numbers make clear that the Biden administration does not have operational control of the border,” House Judiciary Committee Chair Jim Jordan said during a February hearing. “Month after month after month, we have set records for migrants coming into the country and frankly, I think it’s intentional.”

Mayorkas has previously said his department will cooperate with committees that are conducting oversight. Asked by reporters whether launching impeachment proceedings against the secretary was personal, Mayorkas said: “If somebody else was in this position do you think that vitriol would be less? I don’t take it personally. I take my work personally.”

The Biden administration faces unprecedented movement across the Western hemisphere that has contributed to a surge of migrants at the border, including more people from different countries, such as Cuba, Venezuela and Nicaragua. The US is largely barred from deporting migrants to Cuba and Venezuela, presenting a unique set of challenges for DHS.

US border authorities encountered migrants more than 2.3 million times along the US-Mexico border in fiscal year 2022, according to US Customs and Border Protection data. Of those, more than 1 million migrants were turned away at the border.

In early January, the Biden administration expanded a humanitarian parole program to include Haitians, Venezuelans, Nicaraguans and Cubans to provide a legal pathway for them to enter the US instead of crossing the border. The administration also made those nationalities eligible for Title 42, meaning they can now be turned away by authorities if they don’t apply for the program.

Since then, there has been a significant decline in migrants from Cuba, Haiti, Nicaragua and Venezuela crossing the US-Mexico border unlawfully, according to the Department of Homeland Security, which attributed the drop to new border measures.

This story has been updated with additional details.