Who gets to declare war? Senators warn Trump he doesn’t have the power, others disagree

The U.S. Senate is divided over how to respond to the possibility that President Donald Trump may authorize a strike on Iran.

Many Democrats and some Republicans who are opposed to hostilities with Iran argue that Trump lacks the power to make such a move.

“The Constitution says the prerogative to declare war, the power to declare war, is solely from the Congress,” Kentucky Sen. Rand Paul, a Republican, told Fox News.

“It can’t originate from the White House. There is no constitutional authority for the president to bomb anyone without asking permission first. There’s really no argument for why he couldn’t obey the Constitution. Now, my hope is that he won’t do it, his instincts for restraint would prevail,” he added.

Any military intervention in Iran must come before Congress.

This wouldn’t be a surprise attack. There’s no excuse to bypass debate. Thank you for having me, @Timcast pic.twitter.com/oHQNQObUgz

— Senator Rand Paul (@SenRandPaul) June 18, 2025

Louisiana Sen. John Kennedy, also a Republican, somewhat disagreed.

“If you’re suggesting should the president come to Congress first [before] making that decision, it’s conditioned upon what year you want Congress to make a decision,”  he said. “Sometimes it takes us months, even years, to get nothing done.”

Fair point.

Senate Majority Leader John Thune, a Republican, meanwhile, said that Trump is “perfectly in his right to do what he’s done so far,” especially in light of his goal of preventing Iran from obtaining a nuclear weapon.

Pennsylvania Sen. John Fetterman, a Democrat, agreed, arguing that a strike to destroy Iran’s nuclear capabilities would not be a so-called war.

“We have a very specific mission to destroy the nuclear facilities,” he told Fox News. “That’s not a war. That is a necessary military exercise to destroy a nuclear facility.”

Fetterman stands alone among Democrats, the majority of whom are clamoring to stop Trump from pushing ahead.

On Monday, Virginia Sen. Tim Kaine, a Democrat, introduced a war powers resolution that would immediately “terminate the use of United States Armed Forces for hostilities against the Islamic Republic of Iran … unless explicitly authorized by a declaration of war.”

I’m concerned by the escalating violence in the Middle East and its potential to pull us into an endless war. I introduced a resolution to ensure there’s a debate and vote in Congress before we decide to place servicemembers into harm’s way. https://t.co/NCLIMnPZCv

— Senator Tim Kaine (@SenTimKaine) June 17, 2025

Read more about my resolution to prevent war with Iran here: https://t.co/Mw0Hs5UM5E.

— Senator Tim Kaine (@SenTimKaine) June 16, 2025

“It is not in our national security interest to get into a war with Iran unless that war is absolutely necessary to defend the United States,” Kaine said in a statement. “I am deeply concerned that the recent escalation of hostilities between Israel and Iran could quickly pull the United States into another endless conflict.”

“The American people have no interest in sending servicemembers to fight another forever war in the Middle East. This resolution will ensure that if we decide to place our nation’s men and women in uniform into harm’s way, we will have a debate and vote on it in Congress,” he added.

A number of other Democratic senators have echoed Kaine’s concerns.

“The President does not have the authority to make this decision,” Connecticut Sen. Chris Murphy tweeted Monday. “There is no imminent threat to America from Iran. He cannot take this action without congressional authorization. I will not vote to give him that authority, and I likely represent the majority of Congress.”

Delaware Sen. Chris Coons also chimed in via Twitter/X:

The US was at war in Afghanistan and Iraq for 20 years. We should not sleepwalk into another one. The administration needs to come to Congress immediately for a classified briefing on their strategy rather than tweeting our servicemembers in the Middle East into graver danger.

— Senator Chris Coons (@ChrisCoons) June 17, 2025

The debate is also ongoing in the U.S. House, but with a twist. Over there, Kentucky Rep. Thomas Massie, a Republican, and California Rep. Ro Khanna, a Democrat, have introduced a joint resolution that would force the president to obtain congressional approval before striking Iran.

This is not our war.

But if it were, Congress must decide such matters according to our Constitution.

I’m introducing a bipartisan War Powers Resolution tomorrow to prohibit our involvement.

I invite all members of Congress to cosponsor this resolution.

— Thomas Massie (@RepThomasMassie) June 16, 2025