The Trump administration has lost the support of at least two Republican senators over how it handled the killing of Iranian military commander Qasem Soleimani, after top national security officials failed to tell lawmakers when, if ever, they would notify Congress about future military strikes.

Sen. Mike Lee (R-Utah), standing beside Sen. Rand Paul (R-Ky.), lit into Secretary of State Mike Pompeo, CIA Director Gina Haspel, Defense Secretary Mark T. Esper and Chairman of the Joint Chiefs of Staff Gen. Mark A. Milley on Wednesday, telling reporters they refused to answer specific questions during a closed-door session he described as a “drive-by notification or after-the-fact, lame briefing” that was both “insulting” and “completely unacceptable.”

Several senators tried to press officials on why the administration had not approached Congress to authorize the operation to kill Soleimani, and whether there was any situation in which the Trump administration would see fit to approach Congress in advance of a strike.

“They struggled to identify anything,” Lee said, visibly agitated, calling that approach both “un-American” and “unconstitutional.”

As a result of the briefing, Lee pledged, along with Paul, to join Democrats in backing a war powers resolution from Sen. Tim Kaine (D-Va.) ordering the removal of forces engaged in hostilities against Iran, which could come up for a vote early next week. He added that he would be willing to consider other war powers resolutions in the future, as well as “every time they pull a stunt like this.”

House Speaker Nancy Pelosi (D-Calif.) announced earlier that the House would vote on similar legislation Thursday because Trump “has made clear that he does not have a coherent strategy to keep the American people safe, achieve de-escalation with Iran and ensure stability in the region.”

It is expected to pass but not have the force of law — as the House would likely have to pass the Senate’s resolution in order to send the measure to Trump’s desk.

Lee and Paul, who represent the GOP’s more libertarian wing, have broken with Trump previously over activities in the Middle East, backing a measure last summer to require congressional authorization before engaging in hostilities with Iran, and a war powers resolution to end U.S. support for the Saudi-led military campaign in Yemen.

But their declaration is striking nonetheless, coming immediately on the heels of back-to-back briefings in the House and Senate, and an address from Trump in which he declared that Iran “appears to be standing down” and de-escalating the conflict.

Most Republicans emerged from Wednesday’s briefings satisfied with the administration’s legal defense of the strike to kill Soleimani in Baghdad on Jan. 3, action, they said, that rested both on the president’s constitutional authority as commander in chief and the 2002 authorization for use of military force (AUMF) that Congress passed to pave the way for the 2003 invasion of Iraq.

Sen. Lindsey O. Graham (R-S.C.) told reporters that Lee and Paul were “overreacting,” and that senators endorsing a war powers act to restrain Trump’s Iran response were “empowering the enemy.”

“Congress authorized the deployment of troops to Iraq. Implicit in that authorization is the idea that we have an obligation to protect those troops if they are under threat,” Sen. Marco Rubio (R-Fla.) said. “Not only is it part of that AUMF, it is a logical extension of that AUMF that if you authorize troops to go somewhere, they have a right to defend themselves.”

But Democrats found the administration’s legal argument “sophomoric and utterly unconvincing,” as Rep. Gerald E. Connolly (D-Va.) put it, noting it was “absurd” to cite the 2002 authorization because it “of course had nothing to do with Iran.”

If House Democrats left their briefing exasperated, Senate Democrats left with a feeling that it was unfinished. According to Kaine, Senate Minority Leader Charles E. Schumer (D-N.Y.) asked the briefers to pledge they would return to the Hill to finish answering members’ questions.

Lee and Paul shared in that frustration — noting that the briefers could have afforded more time to the lawmakers responsible for their budgets, confirmation and authorization of their military ventures.

“They had to leave after 75 minutes while they’re in the process of telling us we need to be good little boys and girls and run along and not debate this in public,” Lee said. “I find that absolutely insane. I think it’s unacceptable. We never got to the details.”

Lee said that the briefers frequently refused to answer detailed questions, arguing that specifics were “really sensitive,” despite the briefing taking place in a secure facility. Graham, a confidante of Trump’s, argued that it was critics — mainly Democrats — who “don’t want specifics,” calling himself “disappointed” that so many lawmakers kept pressing the briefers to justify the attack instead of applauding the mission.

“To keep asking questions about imminence — I mean the guy’s a designated terrorist, has been killing Americans for decades, he’s on the ground in Iraq, our embassy’s being attacked, we’ve got real-time intelligence of forthcoming attacks without specific places, he’s supposed to be going back to Iran to talk about it. . . . Makes sense to me given the intel they had to hit him,” Graham said. “I would only imagine what people would be saying if we didn’t hit him, given what we knew.”

In the days since the strike, Democrats have taken pains to state plainly that they thought Soleimani was a bad guy but argued that the strike to kill him was still “reckless,” considering its potential to escalate tensions in the region.

At the same time, administration officials have delivered mixed public messages about whether the Soleimani strike was payback for past attacks on Americans, or a preemptive move to avoid an imminent attack. Following the briefings, it appeared some lawmakers still had mixed impressions about which consideration had played a primary role.

Sen. Roy Blunt (R-Mo.) said the administration “made the case that there was an imminent plan” for an Iranian-backed attack that would happen within “days.” But when Sen. Elizabeth Warren (D-Mass.) was asked if the briefing had convinced her there was an imminent threat, she offered a flat “No.”

“It was clear there was a threat,” Sen. Jeanne Shaheen (D-N.H.) offered on her way out of the briefing, seemingly splitting the difference. When asked if it was imminent, she repeated: “There was a threat.”

Seung Min Kim and Paul Kane contributed to this report.