The Senate on Tuesday blocked a resolution that would have required congressional approval before President Donald Trump could continue certain military operations involving Iran.
The measure failed by a 48-47 vote.
The outcome handed the White House a narrow but significant victory in an ongoing debate over executive war powers.
Sen. Raphael Warnock, a Georgia Democrat, introduced the resolution and argued that Congress should play a greater role in decisions involving military action.
Warnock urged lawmakers not to “sit back” while the president makes decisions about potential conflicts abroad.
Most Republicans disagreed.
The vote largely followed party lines but featured notable defections from both parties.
Republican Sens. Susan Collins, Bill Cassidy, Lisa Murkowski, and Rand Paul voted with Democrats to advance the measure.
At the same time, Democratic Sen. John Fetterman voted with Republicans to defeat it.
Fetterman’s vote proved decisive.
Without his support, Democrats were unable to secure enough votes to move the resolution forward.
The Pennsylvania senator has increasingly broken with his party on several foreign policy and national security issues.
His vote against the Iran resolution continued that trend.
The four Republican senators who crossed party lines have each previously supported stronger congressional oversight of military action.
Paul has long advocated for limiting executive war powers and requiring greater congressional involvement in military decisions.
Collins and Murkowski have also occasionally broken with Republican leadership on national security and constitutional issues.
The vote came shortly after Trump announced what he described as an agreement between the United States and Iran aimed at ending months of tensions and military conflict.
“The Deal with the Islamic Republic of Iran is now complete. Congratulations to all!” Trump wrote on Truth Social.
The administration has not publicly released detailed terms of the agreement.
That lack of information has prompted questions from lawmakers in both parties.
Senate Majority Leader John Thune said Congress is seeking additional information about the arrangement and how it would be implemented.
Questions have also emerged about whether the agreement could trigger provisions of the Iran Nuclear Agreement Review Act.
That law requires Congress to review certain agreements related to Iran’s nuclear program before sanctions relief can take effect.
Administration officials argued that the resolution was unnecessary and maintained that portions of the War Powers Resolution are unconstitutional.
Officials also contended that an April ceasefire changed the timeline governing congressional authorization requirements.
Those legal arguments were not directly addressed during Tuesday’s vote because the measure failed to advance.
Senate Minority Leader Chuck Schumer indicated that Democrats may continue pursuing other legislative options.
Schumer said lawmakers are discussing a separate proposal sponsored by Sen. Tim Kaine and are attempting to attract additional Republican support.
The House has already approved separate legislation seeking to limit unauthorized military operations involving Iran.
That measure has not yet been considered by the Senate.
The debate reflects a long-running constitutional dispute over the balance of power between Congress and the president in matters of war and foreign policy.
Congress has the authority to declare war, while presidents have historically exercised broad authority as commander in chief.
Successive administrations from both parties have argued that portions of the War Powers Resolution improperly restrict presidential authority.
For now, Trump’s military authority remains unchanged.
The Senate’s failure to advance the resolution means no new restrictions will be imposed through this legislation.
Several questions remain unresolved, including the details of the administration’s agreement with Iran and whether Congress will pursue additional efforts to limit executive authority.
The Kaine proposal remains under discussion.
The House-passed legislation also awaits Senate consideration.
Tuesday’s vote demonstrated how closely divided Congress remains on questions involving war powers, presidential authority and U.S. policy toward Iran, Breitbart News reported.
For the moment, however, the White House has prevailed, and efforts to impose new congressional restrictions on the president’s authority have fallen short.