A bipartisan group of senators unveiled legislation on Wednesday designed to end U.S. support for the Saudi-led war in Yemen. The resolution — introduced by Sens. Bernie Sanders, I-Vt.; Chris Murphy, D-Conn.; and Mike Lee, R-Utah — attempts to use the War Powers Act of 1973, a Vietnam War-era law that limits the president’s power to wage war without congressional authorization, to disentangle the U.S. from a campaign that has claimed thousands of civilian lives and led to mass starvation. The U.S. military currently provides vital support to the Saudi-led incursion into Yemen. Saudi Arabia began its bombing campaign in March 2015, aiming to restore Yemen’s former Saudi-backed president, Abdu Rabbu Mansour Hadi, to power. Hadi was deposed in 2014 by a Zaidi Shiite rebel group commonly known as the Houthis. The U.S. has supported the campaign for almost three years, providing targeting intelligence, weapons, and mid-air refueling support for Saudi warplanes. But neither the Obama administration nor the Trump administration has publicly outlined the legal basis for the U.S. role in the conflict.

The Sanders-Lee resolution makes clear that U.S. forces are still authorized to attack Al Qaeda members in Yemen, but requires the U.S. to withdraw its support for the Saudi-led intervention. The resolution is based on the War Powers Act, which requires the president to withdraw forces from “hostilities” after a 60-day time limit unless Congress explicitly authorizes continued action. The resolution will be introduced in the Senate Foreign Relations Committee, but under Senate rules, the sponsors can force a vote on the floor after 10 days. A Lee aide told The Intercept that the procedure was unprecedented, and it’s unclear what type of resistance the process will face from Senate leadership. “It’s never been done before,” the aide said. “We don’t know what to anticipate.” The resolution will likely face stiff opposition from the Trump administration, which has held classified briefings in support of U.S.-backing for the Saudi bombing campaign. And even if it passes, the administration may question Congress’s power to compel the military to end its role in the war. Multiple presidents have disputed the constitutionality of the War Powers Act, and executive branch lawyers would likely dispute whether U.S. support for Saudi Arabia amounts to engagement in “hostilities,” as the law defines them. This isn’t the first time Congress has challenged the executive branch over its rationale for taking part in the war. In April, when the Trump administration was considering an increased and more direct role in the conflict, a bipartisan group of 55 members of Congress signed a letter urging the administration to explain its legal justification. A Democratic House aide told The Intercept that the members of Congress have not received a response from the administration. “Neither President Trump [nor] Attorney General Jeff Sessions has provided a legal and constitutional argument for U.S. participation in the disastrous Saudi-led war against Yemen’s Houthis,” said the aide. Defense Secretary James Mattis also did not respond to an urgent request from the members of Congress for a briefing, the aide added. In September, Reps. Ro Khanna, D-Calif.; Tom Massie, R-Ky.; Mark Pocan, D-Wisc.; and Walter Jones, R-N.C., introduced a similar War Powers resolution to try to force a vote on U.S. support for the war in Yemen. Senior members of both parties, including Rep. Steny Hoyer, D-Md., the Democratic minority whip, initially opposed that effort, as The Intercept first reported in October. That measure also met with stiff resistance from the Saudi government, which maintains one of the largest lobbying operations in Washington. Brownstein Hyatt Farber Schreck LLP, a lobbying firm initially hired by the Saudi government on a $100,000-a-month retainer, met with key lawmakers to influence the resolution. Elizabeth Gore, a former senior Democratic staffer now working as Brownstein policy director on the Saudi account, corresponded by email on November 13 with representatives from the offices of Hoyer and Rep. Eliot Engel, D-N.Y., the ranking member on the House Foreign Affairs Committee, to discuss the “Khanna resolution.” Another Brownstein Hyatt lobbyist, Zachary S. Pfister, corresponded on the same day with the office of Rep. Seth Moulton, D-Mass., to discuss the resolution.

The discussions were held the same day congressional leaders secured a non-binding compromise resolution that no longer invoked the War Powers Act, but instead offered a resolution declaring the war in Yemen outside the scope of the fight against Al Qaeda. The compromise resolution did not call for a halt to U.S. support for the war but did acknowledge that the Pentagon has provided material support to the Saudi coalition’s military campaign. The disclosure of the correspondence was made to the Department of Justice, which tracks foreign lobbying under the authority of the Foreign Agents Registration Act. The Saudi government has gone on a hiring spree in recent years, retaining the services of more than 145 lobbyists over the last two years, making it one of the biggest spenders on lobbying services, both foreign and domestic. The filings also disclose additional efforts by Saudi Arabia’s lobbyists to contend with other congressional challenges to the war in Yemen. Several lawmakers last year tried to use the National Defense Authorization Act, which sets the annual Defense Department budget, to bring a halt to the war. In the House, Reps. Rick Nolan, D-Minn., and Warren Davidson, R-Ohio, offered amendments to the NDAA to influence the war on Yemen. The Nolan amendment would have prohibited the deployment of U.S. troops in the conflict, and the Davidson amendment would have blocked U.S. involvement not authorized by the 2001 Authorization for Use of Military Force. The amendments passed but were later stripped out in conference committee. Alfred Mottur, a prominent Democratic lobbyist with Brownstein Hyatt and a former fundraiser for Hillary Clinton’s presidential campaign, disclosed that he helped Saudi Arabia influence the NDAA amendments. Other Saudi lobbyists stepped in as well. Howard “Buck” McKeon, a former senior GOP representative who retired from Congress to open his own lobbying shop, the McKeon Group, is also paid by the Saudi government to help maintain political support for the war in Yemen. McKeon and his lobbying firm helped his Saudi clients influence the NDAA amendments to Yemen, as well as the Khanna resolution. McKeon, notably, also lobbied lawmakers to support the Trump administration decision to sell so-called precision-guided munitions, or PGMs, to Saudi Arabia, according to disclosures.