The Senate voted Wednesday to end U.S. support for the Saudi Arabian-led coalition’s war in Yemen, bringing Congress one step closer to a unprecedented rebuke of President Donald Trump’s foreign policy.

Lawmakers have never before invoked the decades-old War Powers Resolution to stop a foreign conflict, but they are poised to do just that in the bid to cut off U.S. support for a war that has triggered a humanitarian catastrophe.

The vote puts Congress on a collision course with Trump, who has already threatened to veto the resolution, which the White House says raises “serious constitutional concerns.”

The measure was co-sponsored by Sen. Bernie Sanders, I-Vt., and Sen. Mike Lee, R- Utah. Next, it will move to the Democratic-controlled House, where it is expected to pass.

The resolution passed by a vote of 54 to 46, with seven Republicans breaking with Trump to back the resolution: Sens. Susan Collins of Maine, Steve Daines of Montana, Mike Lee of Utah, Jerry Moran of Kansas, Lisa Murkowski of Alaska, Rand Paul of Kentucky and Todd Young of Indiana.

“The bottom line is that the United States should not be supporting a catastrophic war led by a despotic regime with an irresponsible foreign policy,” Sanders said on Wednesday from the Senate floor. He said a vote in favor of the measure would “begin the process of reclaiming our constitutional authority by ending United States involvement in a war that has not been authorized by Congress and is unconstitutional.”

In its statement threatening a veto, the White House argued the premise of the resolution is flawed and that it would undermine the fight against extremism. U.S. support for the Saudis does not constitute engaging in “hostilities,” the statement said, and the Yemen resolution “seeks to override the president’s determination as commander in chief.”

“By defining ‘hostilities’ to include defense cooperation such as aerial refueling,” the White House statement said, the Yemen resolution could also “establish bad precedent for future legislation.”

Trump’s support for Saudi Arabia has been a point of tension with Congress since the killing of U.S.-based journalist Jamal Khashoggi last year. Lawmakers from both parties have criticized Trump for not condemning Saudi Arabia strongly enough for the killing.

Sen. Majority Leader Mitch McConnell, R-Ky., addressed those tensions when he urged his colleagues to oppose the measure.

“We should not use this specific vote on a specific policy decision as some proxy for all the Senate’s broad feelings about foreign affairs. Concerns about Saudi human rights issues should be directly addressed with the administration and with Saudi officials,” McConnell said from the Senate floor.

McConnell argued the Yemen resolution “will not enhance America’s diplomatic leverage” and will make it more difficult for the U.S. to help end the conflict in Yemen and minimize civilian casualties.

Sen. James Risch, R-Idaho, who chairs the Foreign Relations Committee, argued that U.S. support for the Saudi-led coalition helps facilitate peace talks and withdrawing from the conflict would delay an eventual political settlement.

“We need to stay engaged (in Yemen) with the limited engagement we’ve had,” Risch said.

A similar resolution to end support for the Yemen war passed the Senate in December, but it was not taken up by the then Republican-controlled House.

Approaching its fifth year, the war in Yemen has killed thousands and left millions on the brink of starvation, creating what the United Nations called the world’s worst humanitarian crisis.

Sen. Chris Murphy, D-Conn., said before the vote that the resolution “will be seen as a message to the Saudis that they need to clean up their act.”

“We are made weaker in the eyes of the world when we willingly participate in war crimes, when we allow our partners to engage in the slaughter of innocents,” Murphy said.