(The Hill) — Republican senators are expressing shock and disbelief that conservative allies of former President Donald Trump in the House threatened to strip colleagues who voted for the $1 trillion infrastructure bill of their committee assignments.

The incredulous reactions of Republican senators to a motion filed in the House to boot Rep. John Katko (N.Y.) from his position as the top-ranking Republican on the House Homeland Security Committee because of his vote for the infrastructure bill reveal the chasm that is opening up between the Senate and House GOP conferences.

While Senate Minority Leader Mitch McConnell, R-Ky., has created something of a bulwark against Trump’s complete takeover of the Republican Party, House Minority Leader Kevin McCarthy, R-Calif., has made public shows of loyalty to the former president and done little to rein in the most rambunctious and provocative pro-Trump conservatives in his conference.

The starkly different attitudes among Senate and House Republicans were laid bare this week when Trump’s allies in the lower chamber made a push to punish the 13 GOP colleagues who voted for infrastructure legislation by threatening their committee assignments.

The calls for retaliation are coming from a small number of conservatives in the House Freedom Caucus and are unlikely to result in lawmakers actually being kicked off committees, but the fact that there’s even a serious discussion of it is causing heartburn.

Senate Republicans warn that taking such a drastic step against fellow Republicans over a good-faith policy disagreement would be foolish and dangerous to the long-term health of the party.

“That’s absolutely nuts,” Sen. Mitt Romney, R-Utah, said of talk in the House of stripping Republicans who voted for the infrastructure bill of their committee seats.

“The infrastructure bill was bipartisan. It was voted for by Mitch McConnell,” he said, arguing that it will now be tougher for Democratic leaders to persuade centrists such as Sen. Joe Manchin, D-W.Va., to vote for a bigger climate and social spending bill because funding for popular hard infrastructure priorities moved separately.

“Republicans were smart to support it,” insisted Romney, who was one of 19 Senate Republicans who voted for the infrastructure legislation.

Sen. Richard Shelby (Ala.), the top-ranking Republican on the Senate Appropriations Committee, called the threatened retaliation against House Republicans “draconian.”

Shelby, who has served in Congress since 1979, opposed the infrastructure bill, joining most of his GOP colleagues in voting against the legislation in August.

But he said he’d never heard talk about stripping a lawmaker of a committee assignment because of how he or she cast a vote on a particular piece of legislation.

Another Senate Republican who voted for the infrastructure bill called talk of meting out punishment against House colleagues who voted for the bill “ridiculous.”

“That’s utterly, utterly ridiculous, and McCarthy ought to squelch that,” the lawmaker said. “They don’t have caucus discipline.”

McCarthy has referred a motion by Rep. Dan Bishop, R-N.C., a member of the House Freedom Caucus, to oust Katko as the top-ranking Republican on the Homeland Security panel to the House GOP Steering Committee.

The Steering Committee can refer the motion to the full 213-member House Republican Conference for a vote or ignore it.

Katko told The Hill on Wednesday afternoon that he didn’t know what would happen with the motion.

Senate Minority Whip John Thune, R-S.D., who also voted against the infrastructure bill, warned that retaliating against fellow Republicans who vote for things they believe are in the best interests of their constituents is a dumb move.

“That’s just not a smart thing to do,” he said. “Retaliatory actions like that, I think, are counterproductive in the long run.

“We have that situation over here once in a while where somebody votes for something and it’s disappointing to us but the most important vote is always the next vote, not the last vote,” he added.

Senate Republican leaders suffered a huge disappointment in 2017 when moderate Sens. Lisa Murkowski, R-Alaska, Susan Collins, R-Maine, and John McCain, R-Ariz., voted with Democrats to defeat legislation to repeal the Affordable Care Act, which was a top Republican priority.

But there was no talk whatsoever in the wake of that vote of punishing those lawmakers.

And the show of respect paid off a few months later when all three Republicans voted to narrowly pass Trump’s Tax Cuts and Jobs Act, 51 to 49.

Collins also helped give Trump a major win when she cast a key vote to confirm his second nominee to the Supreme Court, Brett Kavanaugh, after a rancorous confirmation proceeding during which she came under heavy pressure to vote “no.”

Senate Republicans say the bitter infighting among House Republicans raises serious concerns about their future ability to govern if they win back control of the lower chamber in the 2022 midterm elections, which political handicappers now say is a likely prospect.

Thune said the 13 Republicans facing punishment “will be with the Republican conference over there on most issues and if you start isolating and singling out individual votes, it’s not going to be conducive to having a united majority in the long run on issues where you really need it.”

Sen. Rob Portman, R-Ohio, who led the group of centrist Republicans who negotiated the bipartisan infrastructure bill and who attended a signing ceremony at the White House on Monday, said the bill would have been much different if it didn’t have any Republican input.

“I’m hesitant to get involved in House politics, but I think that’s a very bad direction if they go that way,” he said of the prospect of GOP lawmakers losing committee assignments or being punished in other ways for supporting more funding for roads, bridges, airports, public transit and expanded access to broadband internet.

“People voted for the legislation because it was in the interests of their constituents. It’s very popular back home. If you take that approach that you’re going to punish people for voting for what’s in the interest of the people they represent, you may end up with real problems,” he said.

Senate Republicans see the backlash against colleagues who voted for the infrastructure bill as being driven primarily by Trump, who on Wednesday released an invective-filled statement bashing Republican lawmakers for giving President Joe Biden a major policy accomplishment.

“Mitch McConnell couldn’t stop the first Bill so 19 Senators, including himself, joined in. That’s what he does — if you can’t beat them, join them,” Trump fumed in his statement.

But McConnell says he has no regrets about supporting the legislation, which he called a “godsend” for his home state.

He argued that Republicans improved the bill by taking the Democrats’ proposed tax increases off the table and not touching the 2017 tax cuts.

“From my Kentucky point of view, it was extremely good for our state. I’m proud of my vote,” he said.

Scott Wong contributed.