WASHINGTON — The U.S. Senate is preparing to defy President Donald Trump’s support for Saudi Arabia following journalist Jamal Khashoggi’s killing, teeing up an unprecedented floor vote this week to invoke Congress’s war powers to end U.S. military involvement in the Saudi-led war in Yemen.

This week promises a flurry of activity that could curtail U.S. arms sales to Riyadh, and add new sanctions or rebuke of Saudi Crown Prince Mohammed Bin Salman for his alleged role in Khashogghi’s death, according to retiring Senate Foreign Relations Committee Chairman Bob Corker, R-Tenn.

“We have three different efforts underway, all of which have a lot of momentum,” Corker said Thursday after meeting with other senators to negotiate a path forward. “I think it’s really good to have all this happening at the same time. I think it sends a really strong signal.”

Lawmakers are anxious to act, particularly after CIA Director Gina Haspel briefed a small group of senators behind closed doors Wednesday on the CIA's assessment that the crown prince likely ordered Khashogghi’s death at the Saudi consulate in Istanbul.

Trump has frustrated lawmakers by repeatedly avoiding a rebuke of Saudi Arabia, a close ally, pointing to the domestic economic benefits of U.S. arms sales to Saudi Arabia and Riyadh’s role in preventing a spike in oil prices. He, Secretary of State Mike Pompeo and Secretary of Defense James Mattis, have said publicly that there is no definitive evidence or “smoking gun” connecting the Saudi crown prince to Khashoggi’s killing.

The Senate is preparing to vote some time this week on a resolution that would end U.S. military support for the Saudi-led fight in Yemen, which is likely to have the 51 votes necessary to advance to the floor. It’s unclear, however, whether there will be a freewheeling debate or whether GOP leaders will attempt some way to derail a floor vote.

“This is virgin territory,” said the Senate’s No. 2 Democrat, Dick Durbin, of Illinois. “It we get into the War Powers Act and the parliamentarian opens the door for related amendments, we could finally have the most serious foreign policy debate we’ve had in the Senate in two years, maybe six.”

Yemen skeptics in Congress see politics shifting their way — and against Trump The Trump administration just doubled down on Yemen, but opponents in Congress say they are getting stronger.

× Fear of missing out? Sign up for the Early Bird Brief, the defense industry's most comprehensive news and information, straight to your inbox. Thanks for signing up. By giving us your email, you are opting in to the Early Bird Brief.

Because there is no precedent for the resolution, it’s possible that lawmakers might attempt to add amendments unrelated to Congress’s war powers. To block the use of this and future war powers resolutions as all-purpose legislative vehicles, Corker said he will call for a vote to allow only “germane” amendments—which he expects will pass.

But with the war powers resolution, the Senate risks taking a step that, according to Corker, merely sends a message to Saudi Arabia and has no effect on administration policy—even in the unlikely event the measure passes the House and the president signs it.

Not so, said Sen. Chris Murphy, D-Conn., and a sponsor of the war powers resolution with Sen Bernie Sanders, I-Vt., and Mike Lee, R-Utah. If it passes, Murphy said, the U.S. would be banned from refueling coalition aircraft, U.S. troops would be pulled from a joint targeting center and the U.S. would not be able to escalate its presence in the war.

“The administration will say we’re not flying any refueling missions any more, but they can start refueling tomorrow,” Murphy said. “It’s my belief they stopped the refueling to try to stop there from being 50 votes on this resolution.”

Otherwise, Murphy said he sees Corker and other Republicans as attempting a correction on Trump’s “off the rails” Saudi policy. Any action, he said, would have to end Yemen’s civil war—where civilian casualties average 123 per week—for it to pass in the Senate.

“The most important thing is to stop the slaughter of civilians inside Yemen,” Murphy said. “I’m upset about Khashoggi, but I’m much more upset about the fact that this administration has allowed thousands of kids to die inside of Yemen. We need to end that war.”

A bloc of Republicans who hope to see that measure rejected, including Corker, want a different means to signal, if not punish Riyadh. Sen. Marco Rubio, for example, values Saudi efforts against the Houthi rebels in Yemen as a hedge on Iran, a country he sees as a key threat to the U.S.

“I think there needs to be repercussions for what happened, but those repercussions shouldn’t be blowing up the Saudi alliance,” said Rubio, R-Fla. “You can’t lure someone into a consulate, chop them up to pieces and think it’s going to be business as usual.”

Officials showcase more weapons they say link Iran to terror across the region From grenades to short-range ballistic missiles, items recovered across the Middle East are on display in Washington.

The Senate Foreign Relations Committee plans to mark up a bipartisan bill that would impose sanction and both prohibit arms sales and refueling support to the kingdom. It would also penalize anyone preventing humanitarian aid from getting to those in desperate need in war-ravaged Yemen, or supporting the Houthi rebels, a group backed by Iran.

Corker said he would support the bill — “it’s actually real policy, it’s not using war powers” — but it’s unclear what path the bill will take in the waning days of the current Congress to become law. “I think the Menendez-Young effort is likely one that continues into next year,” Corker said.

Sen. Lindsey Graham, R-S.C., said he is supporting that bill, which is sponsored by Sens. Todd Young, R-Ind., and Bob Menendez, D-N.J., and another measure that states Mohammed is responsible for Khashoggi’s murder.

“It’s a one-two punch,” Graham said. “You basically make a definitive statement about whether you think MBS is complicit in the murder of Mr. Khashoggi — I do — and if you get a good vote there, that gives you a reason to impose sanctions.”

Lawmakers are sorting through several proposed measures that condemn Mohammed for his alleged responsibility for Khashoggi’s murder. Corker said it was possible the Senate’s GOP leadership would quickly bring a measure with the right language to the floor, where he predicts, “it passes with 90 votes.”

“It’s beyond doubt in my opinion. He would be convicted in less than 30 minutes if he went before a jury,” Corker said of Mohammed. “I think it’s important for us to pass something in the Senate that strongly condemns what this crown prince has done in killing this journalist.”

Graham, Rubio, Young, and Democrats Dianne Feinstein, Ed Markey, and Chris Coons, introduced a non-binding resolution on Wednesday that says the crown prince is “complicit” in Khashoggi’s murder.