Washington — The Senate rejected another attempt by Democrats to limit President Trump's ability to use military force against Iran on Wednesday, but one new Republican senator voted in favor of advancing the measure. 

A motion to discharge the resolution from committee failed by a vote of 49 to 50. GOP Sens. Rand Paul of Kentucky, Susan Collins of Maine and Lisa Murkowski of Alaska voted with most Democrats in favor of moving forward, while Sen. John Fetterman of Pennsylvania was the sole Democrat to oppose. 

Murkowski had voted against moving forward with previous iterations of the measure. She told reporters that after a key 60-day window passed earlier this month, she had expected to "get more clarity from the administration," but hasn't received that. The Alaska Republican said she "felt that it was now time" to support the measure "so we can discuss our responsibilities" under the War Powers Resolution.

"We're in a different place than we were last time we voted on this," Murkowski said. 

The resolution, led by Sen. Jeff Merkley of Oregon, would have directed the president to "remove the United States Armed Forces from hostilities within or against Iran, unless explicitly authorized by a declaration of war or a specific authorization for use of military force." 

Since the war began on Feb. 28, Senate Democrats have attempted to pass resolutions limiting Mr. Trump's authority in Iran on six occasions. Until the sixth attempt, Paul had been the sole Republican to support advancing the resolutions. After the 60-day threshold, Democrats were hopeful that additional Republicans would join them on the latest attempt. 

The War Powers Resolution of 1973 requires the president to report to Congress within 48 hours of deploying forces if Congress hasn't authorized a declaration of war, and caps any unauthorized engagement at 60 days. But as the deadline approached, the administration said it did not apply, arguing the clock stopped with the ceasefire reached on April 7. Mr. Trump said in a letter to congressional leaders on May 1 that "hostilities" with Iran had "terminated."

Democrats have pushed back on the administration's thinking. Merkley told reporters ahead of the vote Wednesday that he doesn't accept that the 60-day clock is suspended, saying the war is "at a different stage, and it may heat up again."

"But this will be the first vote in which we're looking at it through that lens," Merkley said. 

GOP Sen. Jim Risch of Idaho, the chairman of the Senate Foreign Relations Committee, echoed the administration's view ahead of the vote, arguing that the hostilities referenced in the war powers resolution "do not exist today and have not existed for some time."

"My colleagues on the other side of the chamber keep saying that somehow the administration is not in compliance with a 60-day clock," Risch said. "The operations that began on Feb. 28 have been terminated. The hostilities ended with the April 7 ceasefire. They're over — full stop."

But Democratic Sen. Tim Kaine of Virginia, who spearheaded the war powers push in the Senate, told reporters that the vote posed the first test of Republicans' "fidelity to the principle that they have laid down about what role Congress should play in this most important area." 

Kaine noted that Republicans are facing pressure from their constituents on the war's impact on the economy and high gas prices: "We're starting to hear doubt creep into their words and into their statements, not only just to us, but more generally."

"There will be a day, and it might be soon, I believe, where this Senate will say to the president, 'stop this war,'" he said ahead of the vote. "I don't know that today will be the day, but I believe that day is coming."

Merkley cited an "erosion of support, erosion of enthusiasm, an increase in skepticism among our Republican colleagues about this whole operation." But he outlined two factors that may have weighed on Republicans on the vote: whether they give credit to the ceasefire and the president being overseas in China. He said for Republicans, it "doubles the weight to switch positions while the president's abroad."

Senate Majority Leader John Thune stressed ahead of the vote that "right now, the president is overseas, he's negotiating with the Chinese on a whole range of issues, some of which bear on national security."

"And I think it would be best if everybody hung together and supported the president," the South Dakota Republican said. "But we'll see. People have their own minds about some of these issues."

Merkley said he thinks many Republicans ultimately "are uncomfortable with where they stand, but they're also uncomfortable with being on the wrong side of Trump."

Murkowski, who has said she intends to introduce formal authorization for the use of military force in Iran, questioned Defense Secretary Pete Hegseth about the administration's authority at a hearing on Tuesday. Hegseth said the administration's view is that if the president decides to resume strikes against Iran, "we would have all the authorities necessary to do so."

When Murkowski asked whether it would be "helpful to the president if it was made clear" he had full authority through congressional approval, Hegseth reiterated, "Our view is that he has all the authorities he needs under Article II to execute."