“No more! Enough death. Enough killing. Enough destruction,” thundered Vermont Senator Bernie Sanders, as he called Wednesday for the Senate to end US military assistance for Saudi Arabia’s brutal assault on Yemen in a war that has spawned a humanitarian catastrophe. “The time is now to tell Saudi Arabia that we are not committing to partner with them in this horrific crisis.”

Sanders has stood on the losing side of many battles to reclaim the Senate’s authority in matters of war and peace, and to dial back the US role in distant conflicts. But, this time, his call “for the United States to redefine our relationship with the Kingdom of Saudi Arabia” was heard. And embraced.

On Wednesday afternoon, the Senate voted 63-37 in favor of allowing floor debate on S.J.Res.54, the “joint resolution to direct the removal of United States Armed Forces from hostilities in the Republic of Yemen that have not been authorized by Congress” that Sanders has advanced with Senators Chris Murphy (D-CT), Mike Lee (R-UT), and 14 other co-sponsors.

All 49 Democrats in the Senate backed the resolution, which pushes back against the Trump’s administration’s alliance with the Saudis. They were joined by 14 Republicans, including Senate Foreign Relations Committee chair Bob Corker (R-TN), who rejected pressure from the White House that grew so intense that it inspired a midday New York Times headline reading: “Trump Officials, Fiercely Defending Saudis, Warn Senators Not to Abandon Yemen War.”

Secretary of State Mike Pompeo told senators that the vote was “poorly timed.” Activist groups such as Peace Action disagreed, pointing to an emergency alert from the group Save the Children that warns: “As the war in Yemen enters its fourth year—children in Yemen are facing a massive crisis. The volatile civil war, taking place in the midst of growing poverty, is causing the world’s worst humanitarian emergency. More than 11 million children urgently need lifesaving assistance. Countless more children are at risk of starvation as Yemen edges toward the brink of famine.”

They recognized the urgency of the latest assessment from Tamer Kirolos, Save the Children’s Country director for Yemen, who says, “We are horrified that some 85,000 children in Yemen may have died because of extreme hunger since the war began. For every child killed by bombs and bullets, dozens are starving to death and it’s entirely preventable.”

Peace Action, Code Pink, MoveOn, and other groups targeted wavering senators with a social-media campaign featuring the message #YemenCantWait. That was a rebuke to House Speaker Paul Ryan (R-WI) and members of the House Republican Caucus, who blocked a move by California Democrat Ro Khanna to force a vote on a measure similar to the one Sanders advanced.

The Senate vote may create a new opening for action in the House. But the focus in coming days will be on the Senate, where activists and their congressional allies will struggle to secure approval for the Sanders resolution. The measure still faces significant procedural hurdles, and could be restructured and amended before a final vote takes place. While Sanders focused on humanitarian and constitutional concerns, many of the senators who supported opening debate spoke about their desire to send a message regarding the murder of journalist Jamal Khashoggi inside the Saudi consulate in Istanbul. There are no guarantees that every senator who voted to bring S.J.Res.54 to the floor will hold firm in the face of lobbying and veto threats from the White House.

But Sanders expressed confidence that sentiments in the Senate are shifting. He explained that the Khashoggi killing “has exposed the Saudi government to be a brutal, despotic regime which will do anything to anybody to maintain its influence and power.”

No matter what the final outcome, the Senate vote on Wednesday represented a dramatic turn in the debate over Yemen. Earlier this year, a majority of senators rejected a move by Sanders to force a vote on his resolution. On Wednesday, the overwhelming majority stood on the right side of history.

“For the first time, the U.S. Senate voted to advance a resolution withdrawing U.S. Armed Forces from an unauthorized and unconstitutional war. The situation in Yemen now is the worst humanitarian disaster in the world. Eighty-five thousand children have already starved to death and millions more are on the brink of starvation. All of which was caused by Saudi intervention in the civil war in Yemen,” Sanders said after the vote. “The bottom line is the United States should not be supporting a catastrophic war led by a despotic regime with a dangerous and irresponsible military policy. Let us bring this catastrophic war in Yemen to an end, help bring peace to this tortured country and with the rest of the world help provide the humanitarian aid that is so desperately needed.”

Peace Action’s Paul Kawika Martin echoed the sentiments of the senator, saying, “Three years ago, the notion of Congress voting to cut off military support for Saudi Arabia would have been politically laughable. This successful vote in the Senate is a testament to the collective power of a coalition of peace groups, human rights groups, and grassroots activists across the country making calls, organizing rallies, and meeting with members of Congress to make the case for ending the U.S. role in the war in Yemen. Of course, more work remains to be done. The Senate still needs to pass the Sanders resolution itself and the House needs to follow suit as soon as possible to force the president to decide between vetoing the legislation, which polls suggest would be widely unpopular, or ending U.S. support for the war.”