By Caitlin Yilek
March 4, 2026 / 6:00 AM EST / CBS News
Washington — The Senate will vote Wednesday on whether to block President Trump from using further military force against Iran, after the administration launched a large-scale military operation over the weekend and offered shifting explanations about its goals.
Sen. Tim Kaine, D-Va., forced the vote with a war powers resolution cosponsored by Republican Sen. Rand Paul of Kentucky that would “direct the removal of United States Armed Forces from hostilities within or against the Islamic Republic of Iran that have not been authorized by Congress.” Kaine previously forced a similar vote in June, after U.S. strikes on sites tied to Iran’s nuclear program, but that effort failed.
With Republicans holding a 53-seat majority, the measure is expected to fall short of the simple majority needed to advance. Sen. John Fetterman, D-Pa., has pledged to vote against the resolution, meaning it would need support from at least four Republicans in addition to Paul. In June, most Democrats and Paul supported the Iran resolution while Fetterman sided with most Republicans against it.
Even if Congress approved the measure, it would likely be symbolic: the president could veto it, and overriding a veto would require two-thirds majorities in both chambers. Kaine acknowledged the effort faces long odds but said it’s important to put colleagues on the record about authorization for war. “If you don’t have the guts to vote yes or no on a war vote, how dare you send our sons and daughters into war where they risk their lives,” he said.
The operation in Iran, Mr. Trump said Monday, was projected to last four to five weeks though the U.S. has the “capability to go far longer than that.” He also said the campaign was “substantially ahead of our time projections” and did not rule out deploying ground troops.
Democrats who attended a classified briefing with administration officials on Tuesday said they left unsatisfied and warned of more American casualties. “They told us in there that this is an open-ended operation that hasn’t even really started in earnest yet,” Sen. Chris Murphy, D-Conn., said. “There will be more Americans killed. They refuse to take off the table, the insertion of ground troops.” Sen. Cory Booker, D-N.J., said there was “clearly … no imminent threat.”
A CBS News poll found most Americans disapprove of the war with Iran and feel the administration has not clearly explained its goals; about half of respondents believe the conflict could last months or years.
Senate Majority Leader John Thune, R-S.D., said the administration’s actions were “consistent with what previous administrations have done” and that “the president was perfectly within his rights to take the steps that he took.” Secretary of State Marco Rubio told reporters no presidential administration has accepted the War Powers Resolution as fully constitutional but said the administration “complied with the law 100%, and we’re going to continue to comply with it.”
The Constitution gives Congress the power to declare war. The 1973 War Powers Resolution requires the president to consult with Congress in “every possible instance” before introducing military forces, to report to Congress within 48 hours of deploying forces without a declaration of war, and caps unauthorized engagements at 60 days unless Congress approves.
In a notification to Congress Monday, Mr. Trump cited “repeated efforts to achieve a diplomatic solution to Iran’s malign behavior,” saying the threat to the United States and its allies “became untenable” and adding that “it is not possible at this time to know the full scope and duration of military operations that may be necessary.”
Kaine said he may continue forcing votes in the coming weeks and suggested some senators who initially oppose the resolution could change their minds as the situation evolves. He noted Republicans had at one point supported a war powers resolution related to Venezuela earlier this year before the effort stalled after administration pressure.
Sen. Josh Hawley, R-Mo., who previously supported limits on presidential force in other contexts, said he believes the administration is complying with the law on Iran and intends to vote against Kaine’s resolution. Hawley added he has maintained that ground troops would require congressional authorization.
The Senate vote precedes a similar measure expected in the House later this week.
Ibrahim Aksoy, Patrick Maguire and Grace Kazarian contributed to this report.
In: United States Senate; Iran; Donald Trump
