On Friday evening, the U.S. Senate is set to vote on a high-stakes resolution that could determine whether Congress retains its constitutional authority to declare war—or hands more unchecked power to President Trump. While most Republicans are expected to oppose the measure, all eyes are on Democrats: will they stand united, or will a few defections help Trump expand his war-making powers?
The resolution, introduced by Sen. Tim Kaine (D-Va.), would prohibit the use of U.S. military force against Iran without explicit congressional authorization. It’s rooted in the constitutional principle that only Congress can declare war—a check many fear Trump is now bypassing. Though the resolution only needs a simple majority to pass, its success hinges on every Democratic-aligned senator voting in favor.
That outcome is far from certain. One potential defector is Sen. John Fetterman (D-Pa.), who has voiced concerns about limiting presidential authority in military matters. “I don’t want to restrict any future president from making these kinds of decisions,” Fetterman said Thursday, defending past unilateral strikes by both Trump and President Obama.
However, a source familiar with Fetterman’s thinking says he may not want to be the deciding vote that kills the resolution—leaving his stance uncertain.
The urgency behind the vote stems from Trump’s recent bombing campaign against Iran’s nuclear facilities, which he defended as a necessary warning to Tehran. Yet, intelligence assessments questioned the effectiveness of the strike, saying it may have only delayed Iran’s nuclear program by months. Trump’s dismissive response—relying more on cable news than intelligence briefings—has only intensified calls for Congress to assert its role.
Kaine’s resolution wouldn’t reverse what has already happened, but it would send a clear message: Trump cannot act alone if he decides to strike Iran again.
Still, the White House’s closed-door briefings this week raised more doubts than they answered. Lawmakers left questioning the legality, effectiveness, and decision-making behind the strike—fueling frustration among Democrats that they’ve been sidelined.
Some Republicans—such as Sens. Rand Paul and Todd Young—voted for a similar measure in 2020 and remain undecided now. If even a few Republicans join the effort and all Democrats hold the line, the resolution could pass.
Supporters say the vote is not just about Iran—it’s about reclaiming Congress’s constitutional authority. While the 1973 War Powers Resolution was designed to limit unilateral military action, presidents of both parties have routinely ignored it. Trump’s latest strike, many argue, is just the most extreme example.
Critics of the Kaine resolution—including Fetterman—argue that it could hinder a future president’s ability to act quickly. But constitutional scholars and advocates say that’s exactly the point: presidents are not meant to unilaterally wage war.
“Congress needs to reassert itself,” said Dylan Williams, VP of the Center for International Policy Advocacy. “This would make it clear that Trump—or any future president—cannot bomb Iran again without congressional approval.”
In the House, a companion resolution led by Rep. Ro Khanna (D-Calif.) is also facing resistance, with up to 20 Democrats rumored to be considering a “no” vote.
But the stakes are high. Voting down this resolution won’t be seen as bipartisanship or pragmatism—it will be viewed as a green light for Trump to escalate military action without oversight. Congress would be abdicating its most serious responsibility.
With war and peace on the line, Democrats face a defining moment. Will they uphold the constitutional balance of powers—or stand aside as it erodes?
