Washington — Fractures within the Republican Party have become apparent as the GOP grapples with the massive U.S. and Israeli military operation launched on Iran over the weekend. And the breaks come as lawmakers face votes this week on whether to rein in President Trump’s ability to pursue further military action against Iran without congressional authorization. 

From the president’s usual opponents in his party to some of his most stalwart supporters, the U.S. actions in Iran have prompted strong pushback in pockets of the GOP.

Republican Rep. Thomas Massie of Kentucky is leading the House war powers effort alongside Democratic Rep. Ro Khanna of California. Massie has criticized the strikes in strong terms, claiming the approach is not in line with the “America First” agenda, while saying that lawmakers must go on the record on the issue. 

GOP Sen. Rand Paul of Kentucky, a co-sponsor of the war powers resolution in the upper chamber, has also condemned the move to strike Iran without Congress’ approval, citing the legislative branch’s authority to declare war. 

The House and Senate are set to vote on war powers resolutions this week that would require the president to seek congressional approval to use military force on Iran. And while the efforts are mostly backed by Democrats, they pose key tests for the GOP.

Rep. Warren Davidson, an Ohio Republican, has called on the administration to lay out compelling reasons for the war in Iran. Ahead of this weekend’s attack, Davidson said he would support the war powers resolution in the House “in the absence of new information.” 

“This week we’ll either see real intel, hear a persuasive explanation with a defined mission, and declare war / authorize a mission, or Congress must pass this War Powers Resolution and cease work in Iran,” Davidson wrote on X on Monday. 

Still, many Republicans have hailed the president’s move to strike Iran and take out Iranian Supreme Leader Ayatollah Ali Khamenei. Even some of the conference’s more moderate members have appeared unlikely to back war powers votes later this week to rein in the campaign. 

Republican Rep. Don Bacon of Nebraska, who recently voted to limit Mr. Trump’s ability to further strike Venezuela, has said he’ll vote against the Iran resolution. But he wants Mr. Trump to get congressional authorization for “extended operations,” he told CBS News in an interview last week. 

“When you do multiple operations multiple days in a row for a long time, I think you’re required to come to Congress,” he said. The president said Monday he expects the campaign to last four to five weeks, but “we have [the] capability to go far longer than that.”

In an interview Sunday with Steve Scully on SiriusXM, Bacon argued that Congress shouldn’t shy away from a war powers vote. 

“We shouldn’t fear a war powers resolution,” he said. “We have a congressional responsibility and authorities to be a part of this decision.” 

House Speaker Mike Johnson, a Louisiana Republican, said in a radio interview Monday that Mr. Trump was “fully within his authority as commander in chief to do what he’s done.” Johnson said the attack was a “defensive strike” and “not a declaration of war.” He also said the upcoming war powers vote is a “dangerous gambit” by “reckless Democrats.” 

Beyond Congress, the strikes have drawn heavy criticism from prominent figures in the MAGA orbit, including conservative commentator Tucker Carlson, who told ABC News that the president’s decision to attack Iran was “absolutely disgusting and evil.”

Former Rep. Marjorie Taylor Greene of Georgia, a once-staunch supporter of the president who left Congress after the two had a public falling out, has lambasted the president’s strikes on Iran in a slew of social media posts. Greene stressed that she and a number of so-called America First Republicans campaigned on a commitment to ending foreign wars and not seeking regime change. 

“All we wanted was America FIRST. This is not it,” she said.

In another post, Greene posited that the political lines are being redrawn. 

“And just like that we are no longer a nation divided by left and right, we are now a nation divided [by] those who want to fight wars for Israel and those who just want peace and to be able to afford their bills and health insurance,” she said.