WASHINGTON (AP) — The U.S. House has opened debate ready to impeach Homeland Security Secretary Alejandro Mayorkas Tuesday over border security, a deeply partisan and highly unusual attack on a Cabinet official that has drawn concerns from constitutional scholars and rebuke from Democrats.

Republicans in the House argue that Mayorkas has "refused to comply" with immigration laws, resulting in the record surge of immigrants at the U.S.-Mexico border and has "breached the public trust" by his actions and comments. The House vote on the charges, which Democrats say are untrue and hardly grounds for impeachment, is set for afternoon — but it's unclear if Republicans have enough support.

House Speaker Mike Johnson said he spoke privately with at least two Republican holdouts, acknowledging the "heavy, heavy" decision as he tried to encourage their votes.

"It's an extreme measure," said Johnson, R-La., who can only lose a few Republicans from his slim majority. "But extreme times call for extreme measures."

Not since 1876 has a Cabinet secretary faced impeachment charges and it's the first time a sitting secretary is being impeached — 148 years ago, Secretary of War William Belknap resigned just before the vote.

The impeachment charges against Mayorkas come as border security is fast becoming a top political issue in the 2024 election, a particularly potent line of attack being leveled at President Joe Biden by Republicans, led by the party's front-runner for the presidential nomination, Donald Trump.

Record numbers of people have been arriving at the southern border, many fleeing countries around the world, in what Mayorkas calls an era of global migration. Many migrants are claiming asylum and being conditionally released into the U.S., arriving in cities that are underequipped to provide housing and other aid while they await judicial proceedings which can take years to determine whether they may remain.

The House Democrats are expected to unite against the two articles of impeachment against Mayorkas, calling the proceedings a sham over charges that do not rise to the Constitution's bar of treason, bribery or "high crimes and misdemeanors."

"A bunch of garbage," said Rep. Jim McGovern, D-Mass., ahead of a procedural vote. He called Mayorkas "a good man, a decent man" who is simply trying to do his job.

Even if Republicans are able to impeach Mayorkas, he is not expected to be convicted in a Senate trial where Republican senators have been cool to the effort. The Senate could simply refer the matter to a committee for its own investigation, delaying immediate action.

After House Republicans narrowly cleared a procedural vote Tuesday, putting impeachment on track, the debate launched with a reading of the two articles of impeachment against him.

The impeachment of Mayorkas landed quickly onto the House agenda after Republican efforts to impeach Biden over the business dealings of his son, Hunter Biden, hit a lull, and the investigation into the Biden family drags.

The Committee on Homeland Security under Chairman Mark Green, R-Tenn., had been investigating the secretary for much of the past year, including probing the flow of deadly fentanyl into the U.S. But a resolution from Rep. Marjorie Taylor Greene, R-Ga., a Trump ally, pushed it to the fore. The panel swiftly held a pair of hearings in January before announcing the two articles of impeachment against Mayorkas.

A former federal prosecutor, the secretary never testified on his own behalf, but submitted a rare letter to the panel defending his work.

Tuesday's vote arrives at a politically odd juncture for Mayorkas, who has been shuttling to the Senate to negotiate a bipartisan border security package, earning high marks from a group of senators involved in the effort.

But that legislation, which emerged Sunday as one of the most ambitious immigration overhauls in years, is heading toward defeat in a Wednesday test vote. Trump criticized the bipartisan effort, other Republicans are panning it and Speaker Johnson says it's "dead on arrival."

As Tuesday's two hours of debate were underway, it wasn't completely clear that Johnson, with one of the smallest House majorities in modern times, had the support of almost all Republicans needed to impeach Mayorkas.

Rep. Tom McClintock, R-Ca., announced his opposition Tuesday saying the charges "fail to identify an impeachable crime that Mayorkas has committed."

The conservative McClintock said in a lengthy memo that the articles of impeachment from the committee explain the problems at the border under Biden's watch. But he said, "they stretch and distort the Constitution."

Another Republican, retiring Rep. Ken Buck of Colorado, has also said he is against impeaching Mayorkas. A few other Republicans, who voted to shelve the issue in fall, have yet to announce their votes.

Impeachment, once rare in the U.S., has been used as both a constitutional check on the executive and increasingly as a political weapon.

The House Republicans have put a priority this session of Congress on impeachments, censures and other rebukes of officials and lawmakers, setting a new standard that is concerning scholars and others for the ways in which they can dole out punishments for perceived transgressions.

Experts have argued that Mayorkas has simply been snared in a policy dispute with Republicans who disapprove of the Biden administration's approach to the border situation.

Constitutional law expert Jonathan Turley said impeachment is not to be used for being "a bad Cabinet member." Lawyer Alan Dershowitz wrote, "Whatever else Mayorkas may or may not have done, he has not committed bribery, treason, or high crimes and misdemeanors."

"This impeachment is exactly what impeachment was never supposed to be for," said Deborah Pearlstein, director of the Princeton Program on Law and Public Policy who testified before the panel, in an interview.

Scholars point out that the Constitution's framers initially considered "maladministration" as an impeachable offense, but dropped it over concern of giving the legislative branch too much sway over the executive and disrupting the balance of power.

Three former secretaries of the Department of Homeland Security, Michael Chertoff, Janet Napolitano and Jeh Johnson, said in a letter Tuesday that impeaching the Cabinet official over policy disputes would "jeopardize our national security."

Trump as president was twice impeached — first in 2019 on abuse of power over his phone call with the Ukrainian president seeking a favor to dig up dirt on then-rival Biden, and later on the charge of inciting the Jan. 6, 2021 insurrection at the Capitol. He was acquitted on both impeachments in the Senate.

___

Associated Press writer Kevin Freking contributed to this story.