But despite suspicions Pompeo is trying to build the case to use the 2001 authorization against Iran, it’s not clear the administration would even go that route. Pompeo and his Iran adviser Brian Hook have dodged questions about this in open congressional hearings, saying only that whatever action they took with Iran would be under their legal authorities. But Mark Esper, Trump’s nominee to be secretary of defense, said at his confirmation hearing that the 2001 authorization would not apply to Iran. Instead, he said, the president had the authority under Article II of the constitution as commander in chief. “I don’t think there’s a serious attempt to use [the 2001 authorization] for that purpose,” Thornberry said Saturday. “I don’t think anyone would support it.”

The amendment Slotkin cosponsored would not prevent a strike on Iran in self-defense, which is the likeliest justification Trump would claim for a strike if he did order one. When National Security Adviser John Bolton announced in May that the U.S. was sending a carrier strike group to the region in response to intelligence about Iranian threats, he threatened “unrelenting force”—but in the event “of any attack on United States interests or those of or our allies.”

A similar measure failed in the Republican-dominated Senate. Democrat Chris Murphy of Connecticut expressed disgust at what he called Congress’s abdication of responsibility to declare war in numerous theaters where the United States has recently entered into armed hostilities—in Libya in 201 and against ISIS in Iraq and Syria in 2014. “We have given up on authorizing military force largely because it’s a lot harder than it used to be,” he said at an earlier event at Aspen. “We don’t have armies marching against each other we don’t have peace treaties that wrap up hostilities. It’s harder to define your enemies. It’s much harder to define what victory looks like. And we just stopped doing it.”