WASHINGTON — Republican senators are preparing for a robust vetting of Matt Gaetz, President-elect Donald Trump’s pick to lead the Justice Department, with a keen interest in details from a House Ethics Committee investigation into the former congressman from Florida.

The ethics panel has been investigating Gaetz off and on since 2021, most recently focusing on alleged sexual misconduct, illicit drug use, accepting improper gifts, obstruction and other allegations. But the results of that probe may not become public because Gaetz resigned from the House at noon on Thursday. The Ethics Committee has jurisdiction only over sitting House members.

Trump’s choice of Gaetz was a surprise to nearly everyone, including members of his own party and officials at the Justice Department — in part because of the Ethics investigation, his past legal problems and his reputation as a rabble-rouser in Congress.

A source familiar with the process told NBC News that Gaetz had been consulting Trump on who would be best to run the Justice Department. Gaetz did not ask for the role, that person said, but Trump asked him to take on the job Wednesday morning, just hours before the decision was made public.

Many Republican senators, including members of the GOP-led Judiciary Committee that will oversee Gaetz’s nomination for attorney general, said they’ll want to see the details of the House Ethics investigation into Gaetz.

“I think it would be helpful,” said Sen. Joni Ernst, R-Iowa.

Sen.-elect John Curtis, R-Utah, said he would “absolutely” like to see the findings of the House Ethics Committee investigation, saying, “I don’t know the technicalities, or whether or not we would see that, but I think that would be very relevant.”

The House Ethics Committee was scheduled to meet Friday, three sources familiar with the meeting told NBC News, and one of those sources said that releasing the Gaetz report was expected to be among the topics on the agenda. Punchbowl News previously reported Wednesday that the Ethics panel had planned to release a “highly damaging” report about Gaetz on Friday, citing multiple sources familiar with the probe.

But Gaetz’s resignation complicates things, and the meeting was cancelled, according to a source with direct knowledge.

Although the panel lost jurisdiction over Gaetz when he resigned, there is precedent for releasing ethics reports after or on the same day that a lawmaker leaves Congress. It happened in the case of former Rep. Bill Boner, D-Tenn., two months after he resigned in 1987 to become Nashville’s mayor, and with former Rep. Buz Lukens, R-Ohio, on the day he resigned in 1990.

Sen. John Cornyn of Texas, who sits on the Judiciary panel, said he’d be open to issuing a subpoena to the House panel to collect the evidence it has gathered if the committee decides not to release the report.

“We need to have a complete vetting of the nominees, not only so we know that the nominee is qualified, but also to protect the president,” said Cornyn, a former member of Republican leadership.

“I’m sure it’s not in his best interest,” Cornyn said, referring to Trump, “to have any surprises in the House Ethics Committee report.”

Sen. Lindsey Graham, R-S.C., the top Republican on the Judiciary Committee, said he didn’t think the Senate had the authority to subpoena House records, adding, “I’d go ape s— if they tried to subpoena something over here.”

Graham also said Trump hadn’t consulted him on picking Gaetz. “Elections have consequences. He chose Matt Gaetz. Matt will come before the committee, and he will be asked hard questions, and we’ll see how he does,” Graham said.

Sen. Chuck Grassley, R-Iowa, who is likely to take over as Judiciary chair in January, dodged questions Thursday about whether he wants to see the House ethics report.

“Well, we’ve got a professional staff on Judiciary that will do a full job of vetting, and all those questions will be answered by the vetting process report,” Grassley said.

Asked again whether he wants to see it, Grassley said: “I think we have a vetting process. Let it play out.”

Cornyn and other Republican senators said they believe they’ll get all the key evidence from the ethics investigation even if the report itself never comes to light, thanks to an FBI background check and other research conducted as part of Gaetz’s confirmation process in the Senate.

“I am confident that whatever the information and findings are of the House Ethics Committee will eventually be brought out, either through the FBI background investigation or the committee scrutiny of the nominee or through questioning at the hearing,” said Sen. Susan Collins, R-Maine.

Collins does not sit on the Judiciary Committee but is a moderate Republican whose vote in the full Senate could make or break Gaetz’s nomination.

Under the typical process, once he is formally nominated, Gaetz will be grilled by members of both parties on the Senate Judiciary Committee in at least one public hearing. The panel will then vote on sending his nomination to the Senate floor, where a simple majority is needed to confirm him for attorney general.

If Republicans end up winning the Senate seat in Pennsylvania, which is heading for a recount, Gaetz can lose four votes on the Senate floor and still win confirmation. Trump has also said that he wants the ability to appoint his Cabinet members without a confirmation vote, while the Senate is in recess.

Although many Republican senators expressed bafflement at Trump’s choice of Gaetz on Wednesday, given his lack of experience, the Ethics Committee probe, his successful coup against then-House Speaker Kevin McCarthy, R-Calif., and a Justice Department sex trafficking investigation into the congressman that ended last year with no charges, not one has rejected him outright.

Sen. Lisa Murkowski, R-Alaska, another moderate, seemed to go the furthest, saying Gaetz’s is not “a serious nomination for attorney general” and that it would be “a significant challenge” for him to be confirmed. And Ernst on Wednesday said of Gaetz: “He’s got his work cut out for him.”

In the 18 hours since he was announced as Trump’s pick to lead the Justice Department, Gaetz has already started working the phones and placing calls to some Republican senators to get a read on what his chances are at getting confirmed next year, four sources with direct knowledge of the outreach told NBC News.

Separately, Vice President-elect JD Vance and his team have been making their own calls to Senate Republicans about Gaetz, two additional sources familiar with the calls told NBC News.

Gaetz will have to answer his questions during Senate hearings about past scandals and his qualifications for the role, senators said.

“I have concerns that he can’t get across the finish line,” said Sen. Kevin Cramer, R-N.D. “and we’re gonna spend a lot of political capital — I say we, a lot of people will spend a lot of political capital — on something that even if they got it done, you’d have to wonder if it was worth it.”

Cramer said he has “concerns” about Gaetz, particularly how “disrupted and just really destroyed the House of Representatives for several months” in his successful push to oust McCarthy, which, Cramer said, “accomplished nothing except getting rid of him, and, you know, ruin the reputation of the House of Representatives to the point where they didn’t, they didn’t catch the wave in this most recent [election.]”

Asked directly if he’d vote to confirm Gaetz, Cramer said the Florida congressman would have to make it through the Judiciary Committee first. “I never say what I’ll never do, because I want to hear the case. … I’d be open to it,” Cramer said. “But he’s got a really steep hill to climb to get lots of votes, including mine.”

Asked if any Senate Republicans could cross Trump and vote against his Cabinet nominees generally, outgoing Sen. Mike Braun, R-Ind., said, “A few of them, and I’m not going to say which. You still have to go through that process. And if there’s stuff on your record that doesn’t make sense, you’re probably not going to make it through the process.”