The chairman of the Homeland Security Committee, Rep. Mark Green, launched Mayorkas impeachment proceedings at a peculiar political moment: On one side of the Capitol, a bipartisan group of senators has been engaged in almost daily negotiations with Mayorkas over a landmark border security package. On the other, the House wants to remove him from office.

Opening the hearing, Green (R-Tenn.) said there is “no reasonable alternative but to pursue the possibility of impeachment.”

The House panel has been circling Mayorkas all year, at times expected to lurch ahead with impeachment proceedings against him as the border crossings hit record highs, topping 10,000 on some days. The number has recently dipped.

But impeaching a Cabinet secretary is rare, having only happened once before in the nation’s history when the House impeached Defense Secretary William Belknap in 1876 over receiving kickbacks in government contracts. Going after an official for a policy dispute, in this instance over the claim that Mayorkas is not upholding immigration laws, is unprecedented.

“You cannot impeach a Cabinet secretary because you don’t like a president’s policies,” said the top Democrat on the committee, Rep. Bennie Thompson of Mississippi.

Thompson said evidence throughout the hearings will show that Mayorkas is, in fact, doing his job. He decried the political dysfunction coming from the House Republican majority. “This is not a legitimate impeachment,” he said.

With the House GOP’s impeachment inquiry into President Biden, over his son Hunter Biden’s business dealings, lumbering along as lawmakers work to dig up information, the Republicans are sharpening their focus on the border crossings and the investigation of Mayorkas.

Speaker Mike Johnson gave his nod to the impeachment proceedings.

Green’s committee conducted a multi-part investigation into Mayorkas and the department but kicked the process into high gear when hard-right Rep. Marjorie Taylor Greene pushed forward the impeachment resolution after Johnson won the speaker’s gavel following the ouster of Rep. Kevin McCarthy as speaker.

It remains to be seen if the House investigation will convince lawmakers that Mayorkas’ conduct rises to the level of the “high crimes and misdemeanors” the Constitution specifies for impeachment.

Many Republicans blame Biden for taking actions to stop construction of the border wall and end the COVID-19 era restrictions that prevented many migrants from entering the U.S. Both policies had been championed by former President Trump, who is now the front-runner for the party’s 2024 presidential nomination.

“The evidence documented throughout this report will demonstrate that Mayorkas has been, and continues to be, derelict in the solemn duty to secure the nation’s borders,” the panel’s initial report said.

Green, the chair of the committee, has echoed a baseless racist conspiracy idea known as the “great replacement theory” when he argued recently that Mayorkas’ “intent” by removing fewer migrants than Trump did was to “fundamentally change the population of the United States, and I believe to empower the Democrat party in perpetuity.”

Late Monday, Green said what’s happening on the two sides of the Capitol are “separate,” adding negotiations between Mayorkas and the senators “will go on and hopefully they’ll come to an agreement.”

The Homeland Security Department released a memo noting that Mayorkas and the bipartisan senators are working hard to find “real solutions” to fix broken immigration laws while the House majority is wasting time on “baseless and pointless political attacks” by trying to impeach him.

Sen. James Lankford, the chief GOP negotiator of the border package, who has been in almost daily negotiations involving Mayorkas, said he understands his colleagues’ frustrations. But he encouraged them to focus as he has on legislation to force Biden’s hand.

“Mayorkas is gearing up President Biden’s policies — that’s what a secretary is going to do,” Lankford told reporters. “So you can swap secretaries, the policies are going to be exactly the same.”

Lankford was briefing House and Senate GOP lawmakers privately Wednesday on the border talks, which hit a setback this week. Senators struggled with certain differences, particularly over parole programs to allow immigrants who claim asylum entry into the U.S. as they await court proceedings. Reaching a border deal is key to a broader funding package for Ukraine, Israel and other national security needs.

Over the course of the talks, Mayorkas and Lankford have grown to trust each other as the Cabinet secretary has tried to advocate for an immigration system that brings “order and humaneness,” according to one person familiar with the talks who spoke to the Associated Press on the condition of anonymity.

But any goodwill for Mayorkas has not spread to the House, where Republicans are readying their effort to remove him from office. The Homeland Security Committee plans to hold hearings throughout January with the end goal of impeaching Mayorkas.

During Wednesday’s session, Republicans hammered away at Mayorkas’ performance, saying he’d failed to do his job detaining migrants who didn’t have the right to be in the country and allowed others to remain as they await proceedings.

“We’re going to impeach him,” said Rep. Clay Higgins (R-La.).

The panel heard testimony from attorneys general about the flow of fentanyl to their states often from drug cartels and a law professor about the grounds for impeachment.

Democrats said the hearing was designed by Republicans to score political points instead of improving the immigration system. “Impeachment will not make our borders any safer,” said Rep. Delia Ramirez (D-Ill.).

As the House proceeds with its various impeachment inquiries, not all Republicans have been eager for the undertakings.

Eight Republicans voted in November to put off the final Mayorkas impeachment vote by sending it to committee. And some GOP senators have been caught in a political bind as they try to support, but also distance themselves from, their hard-right colleagues.

If the House agrees to impeach Mayorkas, the case would go to trial in the Senate, where it takes a supermajority to convict. In the Grant-era case, Defense Secretary Belknap was acquitted in the Senate.

“Does his handling of that meet the threshold of ‘high crimes and misdemeanors’? That’s a question we’ll have to get answered,” said Sen. John Thune, the second-ranking GOP leader in the Senate.

Associated Press writers Stephen Groves and Farnoush Amiri contributed to this report.