On Friday evening, the U.S. Senate will take a pivotal vote: whether to uphold Congress’s constitutional authority to declare war—or to hand President Trump the power to unilaterally launch military attacks on Iran. While nearly every Republican is expected to vote against the measure, the real question is whether all Democrats will support it.
The bill, introduced by Sen. Tim Kaine (D-Va.), would prohibit the use of U.S. armed forces for hostilities against Iran without explicit congressional authorization. It only requires a simple majority to pass—a difficult but not impossible threshold.
But a few Democrats might defect. If they do, they could kill the resolution—and hand Trump unchecked military power at a time when he’s shown increasingly erratic behavior.
Just this week, Trump warned that if Iran continues pursuing nuclear weapons, he would order more strikes “without a question.” On Truth Social, he lashed out at critics questioning the success of his bombing campaign, showing signs of growing anger and instability. Giving him free rein now would send a dangerous message: that Congress is willing to cede its war-making authority to a volatile president.
So far, the only Democratic senator to publicly oppose the measure is Sen. John Fetterman (D-Pa.). On Thursday, Fetterman said he didn’t want to tie the hands of future presidents, citing both Barack Obama and Trump as examples of leaders who took military action without congressional approval.
Privately, however, a source familiar with the matter said Fetterman doesn’t want to be the deciding vote to sink the measure—meaning his final position may still be undecided.
Kaine’s resolution reinforces a core constitutional principle: Congress alone has the power to declare war. Though the War Powers Resolution of 1973 technically requires congressional approval for prolonged military action, presidents have repeatedly skirted it. Trump’s recent strikes on Iran are just the latest example.
A few Republican senators, such as Rand Paul and Todd Young—who backed similar measures in the past—are possible swing votes. But without unanimous Democratic support, the resolution likely fails.
Some argue the issue is moot because the bombing already happened and a ceasefire is in place. But Trump’s behavior in the lead-up to the strike proves why Congress must act. He ignored intelligence assessments that Iran posed no immediate threat and appeared to make decisions based on cable news commentary. He has since falsely declared the mission a “total success” and dismissed classified briefings that raised serious doubts.
Even after the bombing, the administration struggled to explain its rationale and the actual outcome of the strikes. Lawmakers who attended a classified briefing said it left them with more questions than answers. This only strengthens the case that Congress must play a more active role in military decision-making.
Passing Kaine’s resolution wouldn’t block future action. It would ensure that such decisions are debated and voted on by the people’s representatives. That’s not weakness—that’s accountability.
“The president does not currently have the legal authority to bomb Iran again,” said Dylan Williams of the Center for International Policy Advocacy. “This measure would make that crystal clear.”
It’s still possible all 47 Democratic-aligned senators vote yes. Fetterman might reconsider. But in the House, up to 20 Democrats could also break ranks, according to Rep. Ro Khanna, who is sponsoring a companion resolution.
Fetterman’s argument—that Congress shouldn’t limit presidential power—is exactly backward. The Constitution already limits it. That’s the whole point. Presidents from both parties have overstepped, and Congress has let them. This vote is a chance to correct that.
Skeptics may argue that rejecting the resolution shows strength or “responsible bipartisanship.” But voting no doesn’t make Congress more responsible—it makes it irrelevant. The president will keep deciding on war and peace alone.
Virtually all Republicans will oppose the measure. But Democrats must be the party that insists on constitutional checks and balances—clearly, consistently, and without apology.
There’s still time to get this right.
