Susan Walsh/AP/File
The House Chamber on December 8, 2008.
CNN  — 

Plenty of House Republicans are privately jockeying for President-elect Donald Trump’s Cabinet. There’s one big problem: Speaker Mike Johnson can’t afford to lose their votes in the next Congress.

GOP leaders in Congress are signaling that Trump can’t poach more of their members after Trump on Monday named long-time loyalist New York Rep. Elise Stefanik as UN ambassador and asked Florida Rep. Mike Waltz to serve as his national security adviser.

At least a dozen more House members — including Armed Services Chairman Mike Rogers and Transportation Chairman Sam Graves — have been discussed as other picks.

But even as the House GOP conference remains one of his strongest bases of support in Washington, senior Republicans acknowledge that the Trump team won’t be able to poach many more of those lawmakers without risking Johnson losing control of what could be another slim majority in 2025. CNN has not yet projected control of the chamber.

“I think we have some really qualified people. But I wouldn’t want to drop us down to a one, two (seat) majority tactically,” said Rep. Kelly Armstrong, who is leaving Congress in January to become North Dakota governor.

“We have a lot of talent. There’s a lot of people who would be really, really good at this stuff,” he said. But, he added, referring to the speaker: “You have to give Mike some room to operate.”

Johnson himself has discussed the dilemma with Trump and said he doesn’t “expect” more members will be leaving. The speaker told reporters on Tuesday that he has talked about this “multiple times a day for the last several days.”

“President Trump fully understands and appreciates the math here, and it’s just a numbers game,” Johnson said, adding that “every single vote will count,” noting unavoidable absences such as serious injuries or illnesses or even a late flight.

After Republicans flipped the Senate last week, the exact makeup of the incoming Congress is still unclear. Johnson and his leadership team are confident they will hold onto their narrow House majority, but the question on most Republicans’ minds is how big their margin will be — an outcome that could determine Trump’s ability to further poach from their ranks. And several Republicans are privately warning that the incoming Trump White House will need to be careful “not to cost us the majority by taking too many people,” according to one person close to GOP leadership.

With the selection of Stefanik, that would already be one fewer vote for Johnson in early 2025. And if Waltz accepts the national security adviser role, that’d reduce GOP numbers even further. Both lawmakers represent safe Republican districts, but their seats wouldn’t be filled right away.

The Trump transition team is keeping the House’s slim majority in mind as the president-elect makes his picks. They believe that if Trump does want more House members, he can “stagger” the special elections so that the majority isn’t vulnerable all at once.

“Trump will pick who he wants and who he thinks is the best person for the role,” a Trump adviser said. “There are ways to go around the House majority question if he decides certain members are best for the job.”

Inside the House GOP, many lawmakers and senior aides have long assumed Stefanik would go to the Cabinet. She and Texas Rep. Ronny Jackson, Trump’s former physician, are considered to have some of the tightest relationships between Trump and the House GOP.

Waltz, a combat-decorated Green Beret who served in Afghanistan, the Middle East and Africa, is a Trump loyalist but was also a policy adviser in the George W. Bush administration.

And there are several other Republicans close to Trump privately eager to join his second Cabinet.

In Florida alone, roughly a quarter of the state’s congressional delegation has been floated. Besides Waltz, Reps. Matt Gaetz, Brian Mast, Byron Donalds, Carlos Gimenez and Greg Steube have all been mentioned as potential picks. And privately, Reps. Anna Paulina Luna and Cory Mills have also expressed interest, according to a Florida GOP source.

The replacement process is slightly simpler in Florida, since GOP Gov. Ron DeSantis could call a special election within a matter of weeks.

But at the same time, Johnson will want to keep as many seats as possible, a source familiar with the matter told CNN, adding that Trump’s move to name Stefanik for UN ambassador could impact the president-elect’s decision-making when it comes to adding other House Republicans to his administration.

Ultimately, the transition process remains a “black box” for many of those House lawmakers who say they are ready to serve if called upon.

There is another option: Trump could poach from the list of House Republicans already planning to leave Congress in 2025. That includes Rep. Garret Graves of Louisiana, who has been floated for Transportation secretary, as well as Rep. Matt Rosendale of Montana, who has been discussed as an option to lead the Department of Veterans Affairs.

Trump also has options in the Senate, with CNN reporting Monday evening that he’s likely to pick Florida Sen. Marco Rubio for secretary of state. But there, too, his team is limited by the math. With CNN not yet projecting races in Pennsylvania and Arizona, Republicans will have at least 52 seats in the chamber.

A half-dozen GOP senators have been discussed as possible nominees, including Sens. Bill Hagerty of Tennessee and Mike Lee of Utah. At least two, Sens. Tom Cotton of Arkansas and Eric Schmitt of Missouri, have taken their names out of consideration.

CNN’s Alayna Treene and Zachary Cohen contributed to this report.