The Senate late Wednesday rejected a measure aimed at restricting President Trump's power to wage war against Iran, in a victory for the president and Senate GOP leadership as they seek to quell congressional discontent with the Trump administration's Iran strategy.

The procedural motion failed in a 50 to 47 vote, with two Republicans — Sens. Susan Collins and Lisa Murkowski — voting in favor of advancing the resolution by Democratic Sen. Tim Kaine, siding with most Democrats. Republican Sen. Rand Paul voted present, and Democratic Sen. John Fetterman voted no.

Just one day earlier, four Republicans voted yes on a separate House-passed war powers resolution, allowing it to narrowly pass. Those same four GOP lawmakers voted to advance the Kaine resolution in an earlier procedural vote last month — the first time an Iran war powers resolution had moved forward in the Senate after seven failed attempts.

Kaine's resolution would direct Mr. Trump to "remove the United States Armed Forces from hostilities within or against Iran," unless authorized by Congress.

The measure's practical impact is unclear since the president would likely veto the measure even if it passes, and the Trump administration has argued the U.S. is no longer engaged in hostilities with Iran since the two sides entered into a ceasefire. The administration has also said it believes the 1973 War Powers Resolution — the law that set up a process for Congress to push back on presidential uses of military force — is itself unconstitutional.

Still, Mr. Trump has publicly and privately vented about the war powers votes, arguing the rebukes from Congress have undermined his efforts to negotiate with Iran.

Those frustrations boiled over earlier Wednesday, when Mr. Trump expressed his discontent during a testy lunch meeting with Senate Republicans, CBS News previously reported. At one point, the president sternly told Republican Sen. Bill Cassidy of Louisiana — who had voted in favor of Tuesday's war powers resolution — to sit down. Cassidy told reporters after the meeting that "[Mr. Trump] raised his voice" and "I lost my temper."

Later in the day, however, signs emerged that some of the Senate Republicans who had previously voted to constrain Mr. Trump's war powers were reconsidering. 

Cassidy was briefed on Iran at the White House by Vice President JD Vance and special envoy Steve Witkoff, the senator confirmed on X, writing that the conversation "address[ed] many of my concerns." Cassidy voted against advancing the resolution Wednesday night.

And Republican Sen. Rand Paul of Kentucky voted present on Wednesday, despite voting in favor of the last several Iran war powers resolutions. He said on X his goal was to "give the President more space and leverage to negotiate a lasting peace."

"My opinion on the debate over war and executive power has not changed and I have voted that way several times," he said. "But since hostilities seem to be over and the President asked me to give consideration to his negotiating position, I will do so."

Senate Majority Whip John Barrasso, a Wyoming Republican, helped "seal the deal" in conversations with some key GOP members, a person familiar with the matter told CBS News.

The back and forth comes after Mr. Trump signed a memorandum of understanding with Iran to extend the two countries' ceasefire for 60 days and launch talks on Iran's nuclear program, aiming to wrap up a war that polling shows most Americans do not believe was worth the cost.