The vote was 55-45 — with eight Republicans joining all Democrats to pass the measure. The tally fell far short of the two-thirds needed to override a presidential veto.
Virginia Democratic Sen. Tim Kaine led the charge on the resolution, which would ban the president from ordering any new offensive strikes against Iran. It would still allow the president to order strikes in cases of self-defense against an imminent attack.
"The resolution just says no war with Iran, unless you come and make that case to Congress. And if you make the case to Congress, in front of the American people, and we all have the discussion, ask the tough questions and conclude, sadly, it's in the national interest, that's one thing," Kaine told NPR. "But if we're not even willing to have that discussion, we shouldn't be forcing people to risk their lives."
Mike Lee said the measure focuses on an imbalance of power that has given way to the presidency and it's time for Congress to reclaim its authority.
"We need congressional authorization. We've been lied to by the Pentagon for years regarding a war that has gone on two decades. That's long enough. ... We don't want any more wars without the people's elected representatives being able to debate," Lee said.