The Senate defeated a war powers resolution on Wednesday that aimed to block President Trump from ramping up the war with Iran, as the operation approaches a fourth week.

In a 53 to 47 vote, a Democrat-led effort to restrict Mr. Trump from taking military action in Iran fell short for a third time. Sen. John Fetterman of Pennsylvania was the sole Democrat to vote against advancing the resolution. GOP Sen. Rand Paul of Kentucky supported it.

The resolution, led by Democratic Sen. Cory Booker of New Jersey, 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." Congress has not authorized military force against Iran.

The vote came as Republicans are holding an unusual and lengthy debate on elections legislation amid pressure by Mr. Trump, who has threatened to withhold his signature from other bills that reach his desk until the measure passes. Democrats were able to force the war powers vote despite the floor takeover because the resolution is privileged.

The Senate had previously defeated an Iran war powers resolution introduced by Democratic Sen. Tim Kaine of Virginia on March 4. It was the second time in less than a year that the upper chamber had voted down an effort to rein in Mr. Trump's ability to strike Iran, following a similar vote after last June's U.S. airstrikes on Iranian nuclear sites.

But as the Iran war approaches the one-month mark, Mr. Trump has yet to make clear an exit strategy and has not ruled out sending ground forces into the country. The president has said he expects the war to end "soon," but hasn't specified a timeline.

After the early March defeat, a group of Democratic senators vowed to keep pressing the issue if Secretary of State Marco Rubio and Defense Secretary Pete Hegseth did not testify in public about the war. The Democratic senators behind the war powers push indicated in a letter to Senate Majority Leader John Thune, a South Dakota Republican, that they would abandon votes on a handful of resolutions if the Trump officials testified at public hearings.

"We're going to use every lever that we have to stop business as usual and force the Senate [to do] what it should have done already," Booker told reporters earlier this month.

Sen. Chris Murphy, a Connecticut Democrat, accused the Trump administration of dodging public hearings on Iran out of fear of losing any public support for the war.

"I don't think they can defend this war," Murphy told reporters earlier this month. "I think they'll lose votes in the Senate if they actually have to go in front of the American public and explain why gas prices are so high, explain whether we're engaged in regime change or whether we're not, explain how they're going to get the nuclear weapons and the nuclear material without the ground invasion."

The Trump administration's top intelligence officials testified Wednesday to the Senate Intelligence Committee in a hearing that was pegged to the release of the annual worldwide threats assessment, though questions largely focused on Iran. Director of National Intelligence Tulsi Gabbard deferred to Mr. Trump when pressed on the president's claims that Iran posed an "imminent" threat to the United States.

The administration and most congressional Republicans have argued that Mr. Trump acted within his legal authority when ordering strikes on Iran. In a letter to Congress in early March, the president said the strikes were necessary to eliminate threats.

"Despite my Administration's repeated efforts to achieve a diplomatic solution to Iran's malign behavior, the threat to the United States and its allies and partners became untenable," the president wrote. He acknowledged that "it is not possible at this time to know the full scope and duration of military operations that may be necessary."

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