WASHINGTON – The Senate voted Wednesday to begin debate on a measure that would end U.S. military support for the Saudi-led war in Yemen, a historic step fueled by bipartisan outrage over the kingdom's role in the murder of Jamal Khashoggi.

The 60-39 vote marks the first time Congress has held a full-fledged debate on invoking the War Powers Act, a Vietnam-era law designed to limit the president's power to start or escalate military engagement. Eleven Republicans broke with the Trump administration to support advancing the measure, including Sen. James Risch, the incoming chairman of the Senate Foreign Relations Committee who is usually a reliable ally of the president.

The final outcome remains in flux as senators braced for a free-flowing floor debate on Khashoggi's murder, the U.S. alliance with Saudi Arabia and the war in Yemen. But proponents of the Yemen war powers resolution said they're optimistic it will pass this week. Unlike other bills, the measure is not subject to a filibuster, so it needs a simple 51-vote majority to pass.

“If we end up getting over 50 votes on a war powers resolution, that’s historic,” said Sen. Chris Murphy, D-Conn., who sponsored the Yemen resolution with Sens. Mike Lee, R-Utah, and Bernie Sanders, I-Vermont.

It would be the first time either the House or Senate “has ever used the war powers to pull the United States out of hostilities overseas,” Murphy said.

Senators may vote on a separate resolution, still in the works, naming Saudi Arabia's crown prince, Mohammed Bin Salman, as responsible for Khashoggi's death. The Washington Post columnist was killed inside the Saudi Consulate in Istanbul on Oct. 2 by a team of Saudi operatives.

The crown prince has denied any involvement in Khashoggi's death, but the CIA concluded that he directed the killing. Senators emerged from a briefing with CIA Director Gina Haspel last week saying they were convinced the crown prince, known by his initials MBS, was complicit in the journalist's murder.

Haspel briefed top House lawmakers Wednesday morning. Soon after, House GOP leaders blocked a Yemen war powers proposal from reaching the floor in that chamber. Proponents said they hoped the House would pass it in January, when Democrats gain control of that chamber.

After the briefing, Rep. Eliot Engel, D-N.Y., who will chair the House Foreign Affairs Committee come January, promised a wide-ranging assessment of U.S.-Saudi ties.

“The Foreign Affairs Committee intends to hold hearings after the first of the year about all aspects of Saudi behavior, and we’ll let the chips fall where they may," Engel said.

Sen. Bob Corker, R-Tenn., chairman of the Senate Foreign Relations Committee, is working on the resolution that would implicate MBS. Wednesday, Corker said he would push for a vote on his proposal after the Yemen debate concluded.

Senate Majority Leader Mitch McConnell, R-Ky., argued and several Republicans strongly against the Yemen resolution Wednesday.

“Members on both sides have legitimate concerns about the war in Yemen, about the U.S. interests tangled up in this conflict and especially about the horrible plight of Yemeni citizens who are caught in the crossfire,” McConnell said on the Senate floor. “And where Saudi Arabia is concerned, I think every single member of this body shares grave concerns about the murder of Jamal Khashoggi and wants accountability.”

The GOP leader said American support for the Saudi-led coalition does not amount to military engagement. The United States is not involved in direct combat and stopped providing air-to-air refueling, he noted.

“If the Senate wants to pick a constitutional fight with the Executive Branch over war powers, I would advise my colleagues to pick a better case,” McConnell said.

Lee sharply rejected that argument, noting that the U.S. is providing bombs to the Saudis and helping them figure out what targets to hit. "That’s involvement in war, and that’s pretty direct," Lee argued on the Senate floor.

The war in Yemen has left thousands of civilians dead and created the world's worst humanitarian disaster – millions are on the verge of starvation. It is a proxy battle between Saudi Arabia and Iran, two regimes vying for expanded influence in the region. The United States stopped refueling Saudi jets, but it still provides munitions and intelligence to the Saudi government.

Sanders said the war is "destroying" Yemen, noting that about 85,000 children have died of starvation because of the conflict.

"What I hope today is that we send a loud and powerful message ... that we’re going to get out of Yemen (and) that we’re going to use our resources to bring peace to that country," he said.

The Senate defeated the Sanders-Lee-Murphy resolution this year, but the Khashoggi killing changed the political climate. Republicans and Democrats alike are eager to rebuke the kingdom, arguing that if the United States fails to do that, the crown prince and other autocratic rulers will see that as a green light to commit other extrajudicial killings to silence their critics.

"I’m never going to let this go until things change in Saudi Arabia," said Sen. Lindsey Graham, R-S.C. He is part of a bipartisan group of senators who said Wednesday they would push for a sharper response to Saudi Arabia and the crown prince for the Khashoggi murder in the next Congress, even if the Yemen resolution passes this week.

They're pushing a bill that would impose mandatory sanctions on any individuals found responsible for Khashoggi’s death, including the crown prince, and would suspend U.S. arms sales to Saudi Arabia.

"Do you really want to transfer your most advanced technology to somebody who thinks it’s okay to lure a journalist to a consulate in Turkey … and chop him up?" Graham said, referring to reports that Khashoggi was tortured and dismembered. "The crown prince is so toxic, so tainted, so flawed that I can’t ever see myself doing business with Saudi Arabia" unless there's a change in leadership.

Trump condemned Khashoggi's death but said the incident should not harm U.S.-Saudi relations. The administration relies heavily on Saudi Arabia in its effort to isolate Iran, and Trump championed U.S. arms sales to the regime as an economic boon.

Murphy said he hopes Trump's refusal to punish Saudi Arabia will spark a broader effort by Congress to reassert itself on foreign policy.

"We’ve been sitting in bipartisan meetings for the last week trying to find a way for Republicans and Democrats to reset American policy towards Saudi Arabia," he said. If the Yemen vote is successful, "maybe we can do that on other issues as well."

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