The Senate on Wednesday evening adopted a resolution that scales back U.S. support for the Saudi-led military campaign in Yemen, setting up a showdown with President Donald Trump over his ongoing support for the kingdom.

The GOP-controlled Senate advanced the measure, 54 to 46, marking the first time the body has voted to cease military support for a war in which U.S. involvement hasn't been approved by Congress. Seven Republicans joined Senate Democrats in the vote.

The adoption of the resolution to halt U.S. aid to the Saudis' war effort comes amid civilian deaths and famine in Yemen, which the U.N. has called the worst humanitarian crisis in the world. It also comes as Congress seeks to ramp up pressure on Saudi Arabia after the killing of journalist Jamal Khashoggi.

"Today is an extremely important day. We have the opportunity to take a major step forward in ending the horrific war in Yemen and alleviating the terrible, terrible suffering being experienced in one of the poorest countries on Earth," Sen. Bernie Sanders said Wednesday from the Senate floor.

The Vermont independent, who cosponsored the resolution along with Democratic Sen. Chris Murphy of Connecticut and Republican Sen. Mike Lee of Utah, argued that under the War Powers Resolution, the Senate is "reclaiming constitutional authority by ending U.S. involvement in a war that has not been authorized by Congress and is clearly unconstitutional."

A Saudi-led coalition intervened in Yemen's civil war in 2015 on behalf of the country's internationally recognized government against Iranian-backed Houthi rebels who had taken the capital and ousted the country's president. But the Saudis, who employ U.S.-provided weapons and intelligence, have faced international condemnation for the indiscriminate killing of civilians and for the deterioration of humanitarian conditions that were already considered to be dire.

"It's becoming clearer and clearer that the kingdom of Saudi Arabia is not an ally that deserves our unwavering, unquestioning, unflinching support," Lee said Wednesday. "It is not an ally that deserves our support or our military intervention."

Senate Majority Leader Mitch McConnell said he opposed the resolution, urging fellow Republicans on the Senate floor to reject the measure.

"I strongly oppose this unnecessary and counterproductive resolution and would urge our colleagues to join me in opposing it," the Kentucky Republican said prior to the vote.

Republican Sen. Jim Inhofe of Oklahoma, who also opposed the resolution, argued that the U.S. does not "engage in hostilities" and only provides intelligence.

The vote on the Yemen resolution puts Republicans yet again on a collision course with President Donald Trump, coming as the White House is also scrambling to stave off Republican defectors on a measure that would halt Trump's national emergency at the southern border.

The Senate adopted the Yemen resolution in December with support from seven Republicans, but the measure expired in the last Congress. Last session, the GOP-controlled House didn't take it up. Sanders said Wednesday he expects the resolution will again be brought to the House, where he believes it will succeed.

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If adopted by the House and sent to Trump, it will likely be one of the first vetoes of his administration, along with the disapproval resolution that would block his national emergency declaration to provide funds for a border wall. The White House has already threatened to veto the Saudi resolution, saying in a statement that it would "would harm bilateral relationships in the region." Saudi Arabia has been a linchpin of the administration's foreign policy goal of containing Iran and is expected to figure prominently in its forthcoming Middle East peace plan.

Murphy argued that the resolution is also a response to the death of Khashoggi, who was killed at a Saudi consulate in Turkey. U.S. intelligence concluded that Saudi Crown Prince Mohammed bin Salman ordered the journalist's assassination.

Trump has appeared reluctant to directly call out the crown prince. And the State Department's annual human rights report released Wednesday mentioned Saudi Arabia's killing of Khashoggi but neglected to mention him by name.

Murphy said the Yemen resolution doubles as a response to Khashoggi's death.