WASHINGTON — Sen. Mike Lee of Utah, a libertarian-leaning Republican, has always been a loud but lonely voice in his party clamoring to rein in presidential war powers, so it came as little surprise Wednesday when he questioned President Donald Trump's decision to strike Iran's most important general.

But as Lee emerged from a closed-door, classified briefing with Trump's national security team, he launched into an uncharacteristically indignant tirade that went well beyond his usual staid constitutional arguments about war powers. He blasted the administration for what he called a shoddy briefing on the president's strategy on Iran, delivered in what he described as an "insulting and demeaning" way by administration officials he said were unwilling to engage in a genuine discussion about a possible military escalation in the Middle East.


The message, Lee said, was: "Do not debate, do not discuss the issue of the appropriateness of further military intervention against Iran. If you do, you will be emboldening Iran."

The briefing, scheduled after Trump ordered a drone strike on Gen. Qassem Soleimani in Iraq last week, was led by Mike Pompeo, the secretary of state; Gina Haspel, the CIA director; and Mark T. Esper, the defense secretary. It was, Lee said, "probably the worst briefing I've seen, at least on a military issue, in the nine years I've served in the United States Senate."

The main target of Lee's ire during the session, according to people who attended it and witnessed the contentious exchanges, was Esper, whom the people described as flippant as lawmakers raised serious questions about military action against Iran.

Lee emerged praising Trump for his restraint and saying that he supported the president. But then he launched into a fiery broadside rarely seen in the Senate against Trump's advisers.

"They were in the process of telling us that we need to be good little boys and girls and not debate this in public," Lee said. "I find that absolutely insane. It's un-American, it's unconstitutional and it's wrong."


At one point, he said, as he repeatedly questioned the officials about whether there was ever a circumstance in which they would come to Congress for authorization of military action against Iran, one responded, "I'm sure we could think of something."

Lee has long been willing to cross party lines on the topic of preserving congressional authority, particularly on the issue of war powers. But his angry outburst illustrated the risks for Trump of assuming — as has almost always been the case in the past — that congressional Republicans will feel so loyal to him that they will swallow their reservations about his policies and stay silent, especially on military matters.

And it suggested that when it comes to the president's strategy in Iran, there are at least some cracks in Republican support, as administration officials continue to offer few details on the intelligence that led them to authorize the killing of Soleimani.

Since arriving in the Senate in 2011, Lee has been an outspoken backer of attempts to reclaim Congress' authority, particularly around issues of war and peace. One of the founders of the Article One Project, an initiative intended specifically to enable "congressional rehabilitation," Lee broke party ranks last year to join Democrats in leading a war powers resolution directing Trump to cut off military aid to Saudi Arabia's campaign in Yemen.


Wednesday's briefing, he said, inspired him to again defect from his party and support a war powers resolution led by Sen. Tim Kaine, D-Va., that would limit Trump's war powers on Iran. Lee said he was initially unsure whether he would support the measure, citing some qualms with the wording of the legislation.

"I can say that after that briefing — that briefing is what changed my mind," he said.

Almost all of Lee's Republican colleagues appeared to disagree Wednesday. Sen. Jim Risch of Idaho, chairman of the Foreign Relations Committee, told reporters it was "one of the best briefings" he had ever attended, calling the information the officials relayed "crystal clear."

But Sen. Rand Paul, R-Ky., another libertarian who has worked to insist on congressional war powers, said he agreed with Lee and would also support Kaine's resolution.

"Today, this is Sen. Lee and I saying we are not abdicating our duty," Paul said.

The development was potentially significant, since a War Powers Resolution needs only 51 votes to pass. Republicans control 53 votes in the Senate and Democrats 47, though it is unclear whether all Democrats would support such a measure.

Lee's remarks were lauded by Democrats, who have criticized the administration's briefings and notifications to Congress.

“Thank you,” Kaine said, calling them out by name, “longtime champions of the need for Congress to check presidents’ war-making powers. It’s our constitutional duty.”