Reaction among Republicans on Capitol Hill to President-elect Donald Trump's choice of Matt Gaetz to be his attorney general on Wednesday ranged from shock to support.

Several House Republicans meeting behind closed doors said there was an audible gasp in the room when they heard Trump had picked Gaetz.

Maine Republican Sen. Susan Collins was among those who said they were shocked, appearing to refer to Trump's demand that his nominees be done with recess appointments -- without Senate confirmation.

“This shows why the advice and consent process is so important, and I'm sure that there will be a lot of questions raised at his hearing,” Collins told reporters. “Obviously, the president has the right to nominate whomever he wishes, but I'm certain that there will be a lot of questions.”

Alaska GOP Sen. Lisa Murkowski, who voted to find Trump guilty at his second impeachment trial during his first term, said "I don't think this is a serious nomination for the attorney general."

"We need to have a serious attorney general and I'm looking forward to the opportunity to consider somebody that is serious," she said. "This one was not on my bingo card.”

Gaetz faced a yearslong Justice Department investigation that began in 2019 into allegations related to sex trafficking and obstruction of justice. He has long denied any wrongdoing, and the Justice Department informed Gaetz in 2023 that it was declining to bring charges against him after its investigation.

But the Florida congressman still faces an ongoing investigation by the House Ethics Committee regarding the same allegations.

House Speaker Mike Johnson announced Wednesday night that Gaetz had resigned from Congress effective immediately to "start the clock" on the process for Florida Gov. Ron DeSantis to call a special election to fill his vacancy. Gaetz's resignation will end the probe by the Ethics Committee, which does not investigate members after they have left Congress.

Republican Sen. Mike Rounds of South Dakota, asked if the ethics investigation concerned him, said, “Most certainly, it would be concerning because it would be a part of his file,” Rounds said..Rounds told reporters that he had "no reaction yet" whether Gaetz would be confirmed. Asked if he would vote to confirm, he said, “All I can really tell you right now is that we normally give the president the benefit of the doubt, but we still do our due diligence and advice and consent is still important."

GOP Sen. Cynthia Lummis of Wyoming was vague when asked for her opinion on Gaetz, telling reporters, “I haven’t even had a chance to think about it yet, it’s too new to me.”

Republican Sen. Mike Crapo of Idaho told ABC News that he didn't know Gaetz "so I'll have to dig into it." Asked if Gaetz could be confirmed, he said, "I have no idea, but I assume so."

Florida Republican Sen. Marco Rubio, who, Trump had announced as his pick for secretary of state earlier in the day, had complimentary things to say about his fellow Floridian.

“I've known him for a long time, and again, I think the president is entitled to his team, and he's made his appointments," he said. "And so, I like Matt a lot. I know him very well, and I'm confident that if the Senate confirms him, he would do a good job. And again, the presidents are entitled to have the people that they want in these key positions to carry out the mandate that's been delivered to him by the voters of the United States.”

On the House side, Majority Leader Steve Scalise of Louisiana and House Ethics Committee Chairman Michael Guest, R-Miss., expressed support for Trump's pick. But Rep. Max Miller, R-Ohio, a former Trump aide who was particularly critical of Gaetz following his efforts to oust then-Speaker Kevin McCarthy last year, strongly disputed the choice, predicted Gaetz wouldn't be approved by the Senate.

“I just think it's silly. I believe that the president is probably rewarding him for being such a loyal soldier to the president, but the president is smart enough, and his team is smart enough, to know that Mr. Gaetz will never get confirmed by the Senate. Whatsoever," he said. "And so this is just going to be a very long period of time for him that he's going to get excoriated by members of the Senate on both sides of the aisle, because he's never been a team player, and he's never helped out this conference.”

Miller said that "there's two different types of chaos” -- saying Trump brings one that is positive but the one that Gaetz brings “breaks things.”