Democrats on both sides of Capitol Hill have been forcing votes on President Donald Trump’s military powers this week amid the ratcheting up of tensions with Iran, getting predictably disparate results.

In the latest test, the Senate Foreign Relations Committee on Wednesday turned back a Democrat-led effort to move legislation designed to thwart preemptive military action against Iran.

On a 9-13 vote, with only Republican Rand Paul crossing party lines in support, members of the committee rejected an amendment to Syria-related legislation offered by Tom Udall of New Mexico with the backing of Christopher S. Murphy of Connecticut.

After defeat, Udall offered a dire warning.

“It’s a very important amendment for the timing we’re in,” he said. “At the end of this week, we’re going on break. With this building up, there’s a huge potential for miscalculation. When we return, we could be in the middle of a war.”

Members of both chambers leave D.C. at the end of the week for the Memorial Day recess.

“It’s important that we lower the level of tension and try to put this on the route that if they want to go to war, come in and tell us what your case is and why,” Udall said.

The amendment would block the use of funds “to support kinetic military operations in or against Iran unless such operations are specially authorized by an act or joint resolution of Congress that is enacted after the date of the enactment of this act.”

During a wide-ranging discussion inside the business meeting, senators variously invoked Congress’ constitutional prerogative to declare war, criticized the administration for not providing enough information, and fretted that deferring to Congress to approve military action sends a signal to Iran that the United States is weak.

They were also expecting related votes at the Senate Armed Services Committee. All the action was coming a day after the Trump administration, some would say belatedly, briefed members of the House and Senate on the uptick in tensions with Iran.

The amendment would not have precluded military action against Iran in response to attacks or to rescue Americans. After the markup, Murphy said he knew some Republicans, including Chairman Jim Risch of Idaho and Lindsey Graham of South Carolina, would not support their effort, but he expected some more backing.

“I thought we would get a few more Republicans. It’s unfortunate that they’re lining up behind the president. The amendment doesn’t prohibit us from defending our troops, and it’s disingenuous to suggest that it does,” he said. “But if there’s going to be preemptive war with Iran, the president needs to come to Congress, and I don’t know why we couldn’t all say that.”

Udall offered the amendment shortly after getting back to the Capitol from a bipartisan foreign policy event that focused on getting Congress to reclaim its constitutional powers regarding declaring war, where the New Mexico Democrat was among the speakers.

“One day the president doesn’t want to go to war with Iran, and he wants to talk; the next he wants to annihilate an entire country. I think this Twitter foreign policy is erratic. It’s reckless and it’s dangerous,” Udall said in his speech. “But whether the president wants to wage war with Iran is not the question. The real question is whether [he] comes to Congress to seek a declaration of war against Iran.”

The luncheon where Udall spoke blocks from the Capitol was itself rather usual, as it was a joint production of VoteVets and Concerned Veterans for America, two groups that usually find themselves on opposite sides of political and policy debates.

Speaking at the same event, Rep. Matt Gaetz, an ardent Trump supporter, framed the debate in terms of the president ultimately taking the more reserved option with respect to several international hot spots, whereas more hawkish advisers may have pushed intervention.

“The so-called experts behind our failed foreign policy have not learned from their mistakes because they have never been held accountable for them. And so today the saber-rattling persists, and is directed toward Venezuela, Yemen, and most disturbingly, Iran,” said Gaetz, a Republican from the Florida panhandle. “As we look to these countries, it is our task to ensure that we don’t just recount the mistakes of past decision-makers, but that we learn from them. We must resolve not to start unwise wars or put our military in unwinnable and endless conflicts.”

Back at the Capitol, Sen. Todd Young of Indiana ultimately voted with the bulk of the Republicans after getting assurances from Risch about a new hearing on questions about the authorization for the use of military force.

“If you have a son or daughter or loved one serving in Iraq, this is the worst signal you could send,” Graham said inside the Foreign Relations Committee.

Democrats Chris Coons of Delaware and Robert Menendez of New Jersey (the ranking member on the committee) voted against the Iran amendment. Menendez sounded sympathetic to the intent of Udall and Murphy, but he warned that attaching it to this specific piece of legislation “would sink the entire bill.”

The results were different one day earlier at the House Appropriations Committee, on another military authorization vote that could be viewed as a proxy for the current debate about Iran.

The House committee voted along party lines to adopt an amendment sponsored by California Democratic Rep. Barbara Lee that would sunset the 2001 authorization for the use of military force in the aftermath of the 9/11 terrorist attacks after eight months.

“As the Trump administration escalates tensions with Iran, it is more important than ever for Congress to reassert its constitutional authority. We must start by repealing the overly broad 2001 AUMF and do our job to debate and vote on any replacement,” Lee said in a statement after her amendment prevailed.

Michael Teitelbaum contributed to this report.