The Senate has passed a resolution aimed at ending U.S. support for Saudi Arabia’s ongoing war in Yemen, a rebuke to President Trump that may force him to issue the first veto of his presidency.

The resolution passed by 54-46 with bipartisan support, the culmination of a years-long effort led by Sens. Bernie Sanders (D-VT), Mike Lee (R-UT) and Chris Murphy (D-CT) to claw back Congress’s constitutional war powers and end American support for a humanitarian disaster in Yemen.

“Today, we in the Senate have the opportunity to take a major step forward in ending the horrific war in Yemen, and alleviating the terrible suffering of the people in one of the poorest countries on earth,” Sanders said in a Senate floor speech shortly before the vote. “Equally important, we can finally begin the process of reasserting the Congress’ responsibility over war making.”

Lee decried the “unconstitutional war effort” in “an undeclared war” in his own speech.

All Democrats voted for the resolution, and were joined by seven Republicans.

American involvement in supporting Saudi Arabia and the United Arab Emirates as they lead a brutal effort to defeat Iranian-backed Houthi rebels has drawn increasing scrutiny, with both Democrats and libertarian-leaning Republicans questioning why the U.S. is supporting an effort that has caused such massive civilian casualties. An estimated 85,000 children have starved to death as a result of the war, according to the charitable group Save the Children, and the United Nations has declared the civil war the worst humanitarian disaster on the planet.

Lawmakers’ discomfort with selling weapons to the pair of countries grew further with the Saudi regime’s murder of journalist Jamal Khashoggi, a U.S. legal resident, last fall.

Trump has been unusually supportive of both the Saudis and the UAE, even for an American president — support that’s drawn scrutiny of his and son-in-law Jared Kushner’s business ties with the countries.

“The diplomatic process has been to bear-hug Saudi Arabia in an increasingly warm and bizarre measure,” Murphy told reporters on Wednesday. “If I trusted our diplomats to do the job, then we wouldn’t have to have this debate in Congress, but the Trump administration won’t reset its relationship with Saudi Arabia. So Congress has to.”

The White House has said Trump will veto the measure if it reaches his desk. But its passage through the Senate means he won’t be able to ignore the issue, and highlights the American support of an increasingly brutal campaign that’s caused tens of thousands of civilian deaths.

The vote also shows Congress is shifting some in its stance towards Saudi Arabia, a shift that could matter a great deal should Democrats win the White House in 2020.

This is the second time the Senate has passed this resolution — they did so late last year as well by a 56-41 vote, when Democrats had a few more seats in the chamber . But Republican leaders buried the resolution in the House last year.

This time, House Democrats have already passed a near-identical resolution, though because of an amendment Republicans managed to attach the last time the House will have to vote on a clean version of the bill.