WASHINGTON ― A striking majority of senators voted Wednesday afternoon to move forward a bill ending U.S. support for a Saudi-led coalition fighting in Yemen, offering the biggest condemnation to date of a three-year policy linked to tens of thousands of deaths, hundreds of alleged war crimes and bitter stateside debate under two presidents.

Fourteen Republicans voted with every single Democrat in the chamber to consider a resolution authored by Sens. Bernie Sanders (I-Vt.), Chris Murphy (D-Conn.) and Mike Lee (R-Utah) that demands the policy be ended within 30 days. Thirty-seven senators, including Senate Majority Leader Mitch McConnell (R-Ky.), voted the other way, to preserve without debate the status quo of American intelligence, logistical and diplomatic assistance for the Saudi campaign.

The 63-37 vote represented a huge win for lawmakers and outside groups who had been trying to build support for the anti-war effort since the last time a measure was brought up in March. That resolution failed by a vote of 55-44.

Moreover, intense efforts by the Trump administration to defend the policy ― including a closed-door briefing with senators earlier in the day by Secretary of Defense Jim Mattis and Secretary of State Mike Pompeo ― backfired, as powerful GOP senators like Bob Corker of Tennessee, the chair of the Senate Foreign Relations Committee, and Sen. Lindsey Graham (R-S.C.), a top Trump ally, expressed frustration with top officials.

“I changed my mind because I’m pissed,” Graham, who had previously opposed the measure, told reporters after the vote. “The way the administration has handled Saudi has been unacceptable. The briefing didn’t help me today at all.”

Other senators similarly complained about the failure of CIA director Gina Haspel to appear at the briefing to discuss U.S. intelligence about Saudi authorities’ roles in the murder of journalist Jamal Khashoggi.

The Senate will now debate the measure on the floor within the next few weeks, and it is likely to face numerous amendments that could water it down. Even if it is ultimately passed, it will not compel an end to the U.S. support for the effort by the Saudis and their partner the United Arab Emirates.

Still, Wednesday’s vote was a landmark moment for the increasingly tense debates over who controls matters of war and peace for the U.S. and what to do about the decades-old U.S.-Saudi relationship.