The U.S. Capitol Building in Washington. (Mark Wilson/Getty Images)

House appropriators set in motion Thursday a repeal of the congressional authorization underpinning the U.S. military effort against the Islamic State and recent strikes in Syria, a move that serves as a rebuke of President Trump’s foreign policy and a demand that he present Congress with a plan for how he intends to proceed.

The repeal still has to survive a vote by the full House, as well as the Senate, before it becomes law — a set of hurdles the measure may not be able to clear. But the inclusion of a proposal by Rep. Barbara Lee (D-Calif.) to strike down the 2001 authorization for use of military force (AUMF), which she has offered in years past to no avail, marks a potential turning point for Congress in its ongoing struggle with the White House for a say in how the U.S. military fights extremist groups.

Like the Obama administration before it, the Trump administration has claimed legal authority to conduct strikes and support operations against the Islamic State under the AUMF that Congress passed after the Sept. 11, 2001, attacks to greenlight the war against al-Qaeda and affiliated groups in Afghanistan. Congress has long been divided on the legal argument — a split that has doomed several previous attempts to build momentum behind a new AUMF for fighting ISIS and its affiliates.

But members are finding new common ground in their disdain for the Trump administration’s latest argument: that recent strikes against the regime of Syrian President Bashar al-Assad are also covered under the 2001 AUMF.

“That to me is going way — that’s something that has to be addressed, legally, by Congress,” said Sen. Bob Corker (R-Tenn.), chairman of the Senate Foreign Relations Committee. Corker is among lawmakers who have supported the administration’s argument that the president has the power under the 2001 authorization to conduct strikes against extremist groups but who now also say the authorization does not permit operations against the Syrian government.

According to the Pentagon, a U.S. Navy F/A-18 shot down a Syrian government fighter jet shortly after the Syrians bombed US-backed fighters in northern Syria on 18 June 2017. (Jake Cannady /Us Dod Handout/EPA)

Corker added that he was also uncomfortable with the idea of scrapping the existing authorization with nothing in hand to replace it.

“If you were to do away with the ’01 AUMF and not have one relative to ISIS — then you’re naked; there is no authority,” Corker said. “You have to deal with it simultaneously.”

Most proposals on a new AUMF for fighting the Islamic State do away with the 2001 AUMF and seek to replace it with language more closely tailored to the Islamic State, as well as al-Qaeda and the Taliban. Two of the better-known ideas, a proposal from Sens. Tim Kaine (D-Va.) and Jeff Flake (R-Ariz.), and another from Rep. Adam B. Schiff (D-Calif.), would sunset that new authorization after a few years.

Lee’s proposal would give the administration eight months to come up with a new AUMF before the repeal goes into effect — “sufficient time,” Lee argued, “to decide what measure would replace it.”

There were indications Thursday that Lee’s provision could be snuffed out before it even hits the House floor. Rules Committee Chairman Pete Sessions (R-Tex.) said the provision could run afoul of House rules prohibiting policymaking in spending bills.

“This is by and large policy on an appropriations bill, but it’s an idea we need to understand,” he said, adding that Foreign Affairs Committee Chairman Edward R. Royce (R-Calif.) would be a “co-decision-maker” in evaluating the provision.

Lawmakers in both houses of Congress have argued that to pass an AUMF, the administration must approach Congress with a proposal, however unsatisfactory it may be. The Trump administration has not approached Congress with a proposal, but Corker said he expects Secretary of State Rex Tillerson to at least speak to the Senate Foreign Relations Committee soon about the administration’s “global ISIS strategy.”

Kaine said Thursday he thinks the Foreign Relations Committee may take up his and Flake’s AUMF proposal as soon as next month.

Lee stressed, however, that as long as Congress lets the 2001 AUMF linger, Trump has little or no incentive to seek new legal approval for any military action he orders. She pointed out that in the past 16 years, it has been used 37 times in 14 countries .

“Let me be clear: With the 2001 AUMF still on the books in its current form, any administration can rely on this blank check to wage endless war,” Lee said.