Yesterday, on Dec. 13, the Senate made history. By a vote of 56-41, it adopted S.J. Res. 54, a bipartisan joint resolution that directs U.S. forces to withdraw from “hostilities” in Yemen not related to al-Qaeda within 30 days of enactment—a move that, its supporters maintain, will end U.S. support for the Saudi-led coalition currently waging a military campaign against Yemen’s Houthi rebels. This is the first time that the Senate has ever adopted a resolution pursuant to the War Powers Resolution (WPR), which makes such legislation eligible for certain expedited procedures so as to make it a more effective check against executive authority. Shortly thereafter, the Senate also adopted S.J. Res. 69, a separate proposal that expresses strong opposition to various Trump administration policies in regard to Saudi Arabia and the Yemen conflict.

Neither of these measures is likely to become law or have any legal effect. Their enactment, however, makes clear just how little confidence members of Congress have in the Trump administration’s handling of these issues, even within the president’s own party. Combined with the credible threat of future legislation, this message may finally persuade the White House and Saudi leaders in Riyadh to begin changing their current policies.

What Happened?

For more than 40 years, the Senate has allowed the WPR’s expedited procedure provisions to lie more or less dormant, creating substantial ambiguity as to how debate might proceed pursuant to them. For this reason, the process leading up to the adoption of S.J. Res. 54 provides an important precedent as to how the Senate may choose to make use of these provisions in the future—a model that, in this case, produced an orderly debate process and resulted in clear up-and-down votes on several proposed amendments, without the chaos and unpredictability that some initially feared.

The chain of events leading to yesterday’s vote began on Nov. 28, when the Senate voted 63-37 to discharge S.J. Res. 54 from the Senate foreign relations committee—a vote made possible despite the objections of committee leadership by the WPR’s expedited procedures. The Senate followed up on this vote on Wed., Dec. 12, when it voted 60-39 to proceed to consider S.J. Res. 54. Pursuant to the WPR, this started a statutorily limited ten-hour period of debate, at the end of which the Senate was obligated to take a vote on S.J. Res. 54.

Observers were concerned that this debate would prove chaotic because the WPR explicitly allows for amendments and does not require them to be germane. As a result, Senators could in theory try to attach unrelated amendments to S.J. Res. 54, either to use it as a vehicle to get those measures passed or to undermine support for it by forcing votes on partisan or divisive issues. But these concerns quickly proved to be misplaced.

The Senate’s first item of business following the motion to move to consideration was a point of order by Senate Majority Leader Mitch McConnell making the novel proposal that amendments should be required to be germane, despite the absence of any such requirement in the WPR itself. Following a carefully choreographed exchange between McConnell, the presiding officer and Senate foreign relations committee chairman Sen. Bob Corker, which explained why a germaneness requirement was appropriate, the Senate voted 96-3 in favor. This limited proposed amendments to those that could be considered relevant to—and within the scope of—S.J. Res. 54 as written, preventing efforts to manipulate or derail the process. Later in the evening, the Senate also unanimously consented to limit debate to seven specific amendments (of the more than 20 put forward), during which it appears to have resolved any germaneness concerns.

As a result, debate proceeded in an orderly fashion. Supporters of S.J. Res. 54 spoke more frequently than opponents, most of whom shared concerns regarding the Trump administration’s policies but nonetheless objected to S.J. Res. 54 as a remedy. By Dec. 13, senators were routinely using floor time to take care of other Senate business, including several farewell speeches by departing legislators. This created the unmistakable impression that neither the proponents or opponents of S.J. Res. 54 felt a sense of urgency in debating the measure—a sign, perhaps, that the senators already knew the likely outcome.

Only a small amount of floor time was spent debating amendments before they were brought to a vote. The Senate adopted an amendment by Republican Sen. Todd Young making clear that, for the purposes of S.J. Res. 54 only, the term “hostilities” includes aerial refueling services, along with three amendments from Republican Sen. John Cornyn: two installing reporting requirements as well as a third imposing a rule of construction that S.J. Res. 54 should not be interpreted as limiting any coordination with Israel. Two amendments proposed by Republican Sen. Tom Cotton, which would have avoided withdrawing U.S. support that promoted compliance with the laws of armed conflict or sought to prevent Houthi attacks outside Yemen, were rejected. Supporters of S.J. Res. 54 opposed them on the grounds that they could be interpreted to effectively gut the restrictions that S.J. Res. 54 sought to impose.

With the amendments process complete, the Senate proceeded to a final vote. Once again, every Democratic and Independent senator voted in favor. Seven Republicans ultimately sided with them: Young, Susan Collins, Steve Daines, Jeff Flake, Mike Lee, Jerry Moran and Rand Paul. Three more Republican senators—Lindsey Graham, Thom Tillis and Dean Heller—chose not to vote. The final count of 56-41 was narrower than the prior two procedural votes, reflecting the fact that half of the Republican senators who had supported the initial Nov. 28 motion to discharge ultimately opposed the joint resolution itself. But their willingness to debate the motion still demonstrated their concern with Trump administration policies. And the fact that half of them did ultimately vote for S.J. Res. 54 is a sign of genuine bipartisan support.

Moreover, the Senate did not finish with S.J. Res. 54. As soon as the vote concluded, Corker introduced another joint resolution, S.J. Res. 69. This resolution voiced support for a diplomatic solution to the Yemen crisis, criticized various aspects of Saudi Arabia’s foreign and human rights policy and explicitly held Saudi Crown Prince Mohammed bin Salman responsible for the Khashoggi murder—all clear critiques of Trump administration policies. Modeled on an earlier Senate-only proposal, S.J. Res. 69 was structured as a joint resolution so as to require passage in the House and Senate and then presentment to the president for signature or veto, thereby forcing President Trump to publicly address the Senate’s views. Corker had circulated a version earlier but ultimately agreed to hold off on formally introducing it due to concerns that it might limit Republican support for S.J. Res. 54. Once Corker did so, however, it became clear that the body was already thoroughly familiar with the legislation, as they adopted it through a unanimous voice vote within minutes.

What’s Next?

The enactment of two measures that so openly criticize Trump administration policies is itself notable. But where these measures go from here is less clear. To become law, both would need to be approved by the House of Representatives. Just hours before the final debate on S.J. Res. 54 began, however, the House Republican leadership used a vote on unrelated legislation to introduce a rule change that would prevent an almost identical House resolution—H. Con. Res. 142, sponsored by Democratic Rep. Ro Khanna—from receiving expedited consideration under the WPR. This rule change would not directly affect companion legislation for S.J. Res. 54, which falls under a separate WPR provision that doesn’t provide much in the way of expedited procedures in the House. But the timing of the vote seemed to send a clear message that the House Republican leadership is not willing to let measures like S.J. Res. 54 proceed. Whether the House leadership would be more open to S.J. Res. 69 is less clear, but it seems unlikely.

This most likely leaves it to the next Congress to take up these measures. The incoming Democratic House leadership will no doubt be more willing to take up both measures. And because only one of the seven Republicans who supported S.J. Res. 54 will no longer be in office, the new Senate should be able to secure re-passage as well, so long as Democrats and Independents continue their unanimous support. As for S.J. Res. 69, the real question is whether anyone in the new Senate will take up Corker’s effort after his retirement—and whether they will have the continued support of McConnell, who will likely be able to halt such efforts if he does not wish to see them proceed.

If both measures pass the House and Senate, however, they will still have to survive presentment to the president, who has already stated his intent to veto S.J. Res. 54. And even if two-thirds of both chambers of Congress are able to override his veto, it is not clear what actual legal effect either resolution will have. S.J. Res. 69 only expresses views and does not affect relevant legal authorities. Meanwhile, there is an ongoing debate—even with Young’s amendment—as to whether the definition of “hostilities” used in S.J. Res. 54 reaches current U.S. activities in Yemen. If it does not, as the Trump administration maintains, then it’s not clear that S.J. Res. 54 would require changes in U.S. policy even if enacted.

To account for this possibility, several supporters of S.J. Res. 54 have introduced additional legislation limiting U.S. support for the Saudi-led campaign in Yemen that does not link itself to the WPR’s concept of hostilities. Specifically, the Saudi Arabia Accountability and Yemen Act (S. 3652) sponsored by Young and Democratic Sen. Bob Menendez, would impose substantial legal limits on the Trump administration by suspending arms sales and all but requiring the imposition of sanctions on Crown Prince Mohammed bin Salman for his role in the Khashoggi murder, among other measures. Limited time and disagreements with Corker prevented this bill from receiving a committee markup during this Congress, but Menendez and Young have made clear that they intend to re-introduce it in the next Congress. And during the debate on S.J. Res. 54, several senators—including some who did not ultimately vote in favor of S.J. Res. 54, like Corker—expressed support for this effort.

The difficulty is that such legislation does not qualify for the expedited procedures provided by the WPR. This leaves it vulnerable to filibusters and other methods of obstruction—especially if opposed by McConnell, which seems likely. And even if the legislation makes it through the House and Senate, it will once again be subject to the president’s veto. For this reason, supporters may try to incorporate such restrictions into omnibus legislation that is more difficult for Senate leadership to obstruct and Trump to veto, such as the National Defense Authorization Act. Accomplishing this, however, will take time, effort, and substantial political support in both chambers, as well as the cooperation of committee leadership. But the bipartisan support secured by S.J. Res. 54 suggests this is may be a real possibility.

Why Does it Matter?

Whatever its ultimate legal effect, the political significance of the Senate’s action on the Yemen resolutions should not be underestimated. More than a quarter of Senate Republicans were willing to take at least one vote on in support of S.J. Res. 54, a measure explicitly intended to reverse a central plank of the Trump administration’s foreign policy. Seven Senate Republicans—along with every Democrat and independent—were willing to support that measure through to a final vote. Combined with the unanimous approval of S.J. Res. 69, which condemns many of the same policies, this makes clear to the public just how little confidence members of Congress have in the Trump administration’s decision-making in this area, including many from Trump’s own party.

Perhaps more importantly, S.J. Res. 54 shows that a substantial number of Senate Republicans are willing to turn this discontent into legislation that may well force the executive to change those policies. Especially when combined with incoming House Democratic leadership, this means there is a credible threat of legislation that could take authority away from the president or otherwise limit his ability to execute the foreign policy agenda he is currently pursuing. And while the president’s veto provides him substantial protection from such efforts, using it can come with real political costs. As a result, if a sufficient majority in Congress is determined enough, it will almost certainly succeed at enacting legislative restrictions at some point.

The question is whether the credible threat of such legislation will itself prove sufficient to change the mind of Trump—or King Salman of Saudi Arabia, whose D.C.-based diplomats closely follow U.S. politics. Their more prudent advisors will no doubt urge them to work towards moderating their policies so as to make adjustments on their own terms, not those of Congress, and thereby preserve the broader bilateral relationship. But the Trump administration, at least, has thus far preferred a sharp-elbowed approach that commits the United States to supporting Saudi Arabia no matter the political consequences—and this approach may continue until either Congress or the electoral process reigns it in. Alternatively, if the Trump administration does shift its policies, this may prove sufficient to restore the confidence of Senate Republicans (if not others) and forestall a major legislative response.

Either way, change is coming. And by making the political stakes plain for the world to see, the debate surrounding S.J. Res. 54 may well prove to be the precipitating event that makes it happen.