President Donald Trump clashed with Louisiana Sen. Bill Cassidy in a meeting with Republican senators on Wednesday, multiple sources told ABC News, over the war powers resolution passed Tuesday in the Senate — a rare rebuke of Trump that saw with four Republicans voting with Democrats.

Multiple sources described the clash between Trump and Cassidy as a shouting match. Senate Majority Leader John Thune tried to intervene to de-escalate the situation and other senators tried to jump in to ease tensions over the resolution, which aims to limit Trump’s ability to wage war in Iran but does not have the force of law.

Cassidy was one of four GOP senators who voted with Democrats in favor of the resolution that the House had passed earlier this month. Those votes along with two Republican absences allowed the resolution to pass by a 50-48 vote.

At one point, Trump called Cassidy a “lunatic,” according to multiple sources. Cassidy did not dispute that when asked by ABC News.

Trump was also upset about the absences, sources said.

Briefly stopping to talk to reporters, Trump said the meeting was “really great,” though he did not comment on what was discussed behind closed doors. 

“I think we had a really great meeting, and we’re very proud of the party. We like our leader, we like everybody really in the room,” Trump said. “I don’t like a few people, but that’s OK. I think you know who they are, but we — I’ll give you, I’ll give you that information someday, but for the most part, we have a really well unified party, and I said it very strongly.”

Two people in the room said Cassidy referred to the president as “brother,” but the president told the senator that he was not his brother.

Cassidy admitted that he lost his temper with Trump.

“He asked why would anybody vote for the War Powers Act? As he continued, I said, ‘is that a rhetorical question, or would you like to really know?’ He said, ‘I’d like to know.’ I stood and said, ‘You have not told the American people what’s going on. It was supposed to last four weeks. It’s lasted four months. Our original objectives have not been achieved, and I want to know what’s going on,'” Cassidy said. 

“But that’s kind of what I’ve been saying all along,” Cassidy continued. “I’m voting for war powers until I get a briefing, at which point, as I recall, he did not particularly care for my comments, raised his voice, I lost my temper, that’s not appropriate, it’s the Irish in me, but I again matched his tone and his volume, and it went back and forth. But at some point my guy said, ‘It’s alright, Bill, sit down,’ and so I sat down and tried to de-escalate.”

Cassidy said he made no apologies for standing up to the president.

“The American people just need to know what’s going on with Iran, and I don’t think there’s been sufficient information shared with Congress or with the American people. So that was my message,” he said.

Asked if he regretted how heated the meeting got, Cassidy said, “No, I’m not going to be bullied when I’m trying to ge. for the American people,” he said. “This is not about me, it’s not about the president, it’s about the American people knowing what’s going on, and right now there’s just like it seems like we’re being told different things by different people.

“He may be right. I just think there needs to be more kind of let’s be open about it, and I’m not going to be bullied into silence when I’m sticking up for the American people,” Cassidy said.

Cassidy, who was one of seven Republican senators to vote for Trump’s impeachment in his first term, lost his primary for re-election in May against a candidate Trump recruited to run against him.

Cassidy said in the meeting Trump made a dig at his loss.

“You know, what does President Trump say? You know, ‘Oh, you lost the election,’ that sort of thing. You know, whatever you know comes to mind as to demean another person.”