WASHINGTON ― Rep. Ken Buck (R-Colo.) said Thursday that he opposes impeaching Homeland Security Secretary Alejandro Mayorkas.

Republicans are planning an impeachment vote against Mayorkas next week over his alleged deliberate refusal to detain and deport migrants arriving at the southern U.S. border.

Buck said the border chaos doesn’t amount to a high crime or misdemeanor on Mayorkas’ part and that he’s a “solid” no on impeaching him.

“It’s maladministration. He’s terrible, the border is a disaster, but that’s not impeachable,” Buck told reporters outside the House chamber.

Buck’s opposition will make it more difficult for Republicans to push the articles of impeachment through the House. Depending on how many lawmakers might be absent ― two Republicans are currently out for health issues ― it’s theoretically possible that Buck himself could tank the impeachment effort.

As House Speaker Mike Johnson (R-La.) put it on Tuesday, “We have only a tiny, as you know, razor thin, actually a one-vote majority right now in the House.”

It’s possible that the votes simply aren’t there for the impeachment resolution and it could go down in flames on the House floor, handing Republican leadership a humiliating defeat. There are too many variables in play — member absences, the GOP’s incredibly slim majority, and a number of Republicans not saying how they’d vote — to assume this is a done deal.

Rep. Tom McClintock (R-Calif.), for one, said earlier this week that he’s undecided on how to vote. His office did not respond to a request for comment Thursday.

Rep. Dave Joyce (R-Ohio) is also being coy on how he’d vote.

“Congressman Joyce has met with Chairman Green and is reviewing the material that they have provided,” said Sarah Young, a spokesperson for Joyce. She was referring to Homeland Security Committee Chair Mark Green (R-Tenn.), who this week led the committee in approving impeachment articles.

Several Republicans previously opposed the idea of impeaching Mayorkas, noting that he hasn’t done anything that reaches the legal threshold for impeachment. And if some GOP lawmakers didn’t go that far, they at least raised questions about the point of holding a vote like this. Reps. Dusty Johnson (R-S.D.), Mike Turner (R-Ohio), Patrick McHenry (R-N.C.) and María Salazar (R-Fla.) are among them.

Only one of those four GOP members’ offices responded to a request for comment on whether they support impeaching Mayorkas now.

Johnson spokesperson Kristen Kurtz said that the congressman from South Dakota will vote to impeach.

“In the last few months, the Homeland Security Committee has established that Secretary Mayorkas has engaged in a willful and systemic refusal to comply with the law. Because of his actions, the southern border is in crisis,” said Kurtz. “Accordingly, Congressman Johnson will be voting to impeach.”

Buck’s beef with impeachment echoes criticism from many quarters, including from conservative legal scholars, who have said Republicans are bogusly elevating a policy difference into a high crime.

Buck has previously spoken out against the impeachment inquiry against President Joe Biden, saying that his colleagues lack evidence. However, he ultimately voted with his party to formally authorize the inquiry last year.

Buck, who is not a member of the Homeland Security Committee that approved the impeachment articles against Mayorkas, said that its chair visited him at his office to make the case. He said he’s also speaking to people outside of Congress.

“The people that I’m talking to on the outside, constitutional experts, former members, agree that this just isn’t an impeachable offense,” Buck said.