Washington — The Senate rejected Democrats' sixth attempt to limit President Trump's authority to wage war on Iran, with Republicans continuing to stand behind the administration as the conflict approaches a key 60-day deadline. 

A procedural vote to advance a war powers resolution brought by California Democratic Sen. Adam Schiff failed 47 to 50 on Thursday. The measure would have directed the president to remove American forces from hostilities with Iran.

Republican Sens. Rand Paul of Kentucky and Susan Collins of Maine voted in favor of the measure. Collins had voted against prior Iran war powers resolutions. The only Democrat to vote against the measure was Sen. John Fetterman of Pennsylvania.

The War Powers Resolution of 1973 says the president must remove armed forces from hostilities after 60 days if Congress has not authorized the war. The 60-day clock starts once the president sends formal notification to Congress. Mr. Trump notified lawmakers of the hostilities with Iran in a letter on March 2, meaning the 60-day window closes on Friday, May 1. The president can extend the deadline by 30 days to allow for the removal of troops.

Democrats in both the House and Senate have said they plan to keep forcing votes on the Iran war and have introduced a wave of resolutions in recent weeks in preparation. Members of the Congressional Progressive Caucus have been rolling out one each day since last week. 

The fighting between the U.S. and Iran has been mostly paused for weeks during an ongoing ceasefire, but Democrats have continued to bring votes on whether to limit the president's authority to wage war. Most Republicans have declined to join their efforts, but some have indicated that they might change their tune at the end of 60 days. A handful of GOP senators have said they are working on drafting legislation that would explicitly authorize the use of force against Iran, which would bypass the war powers debate entirely.

Meanwhile, Defense Secretary Pete Hegseth told the Senate Armed Services Committee at a hearing on Thursday that the administration considers the 60-day window to be paused given the cessation of active fighting. 

"We are in a ceasefire right now, which in our understanding means the 60-day clock pauses or stops in a ceasefire," he said. 

Virginia Democratic Sen. Tim Kaine cast doubt on that assertion, saying, "I do not believe the statute would support that."

"That's going to pose a really important legal question for the administration," Kaine said.

House Speaker Mike Johnson told NBC News that Congress doesn't need to act because the U.S. is "not at war."

"I don't think we have an active, kinetic military bombing, firing or anything like that. Right now, we are trying to broker a peace," Johnson said. "I would be very reluctant to get in front of the administration in the midst of these very sensitive negotiations, so we'll have to see how that plays out."