The question is who will benefit most when it finally falls.

To hear Senators Joe Manchin and Kyrsten Sinema tell it, they hoped to defend voting rights. They also hoped, even more fervently, to defend the Senate filibuster.

In the end, they did neither.

It’s true that by joining their Republican colleagues this week to reject a rules change and block a pair of voting-rights bills, the two Democrats ensured that the filibuster remains temporarily intact. But Manchin and Sinema’s goal was not merely to block a piece of legislation or preserve a procedural rule in the short term. As Manchin himself put it, “We must never, ever, ever, ever tear down the only wall, the necessary fence, that this nation has against the excesses of the executive branch and the resultant haste and tyranny of the majority.”

Yet as Manchin also acknowledged, his arguments in favor of the filibuster have failed to persuade. Forty-eight of his Democratic colleagues—including many who supported the 60-vote threshold in the past—decided that voting rights were more important than the filibuster. So did past presidents. So did the current president. So did Stevie Wonder. So did Oprah.

In other words, although the most recent attempt to thwart the filibuster did not succeed, neither did the most recent attempt to defend it for future generations. The filibuster now has three paths forward—and all of them end, one way or another, in its demise.

The first and most obvious possibility is that Democrats will one day win a Senate majority that doesn’t depend on Manchin and Sinema. Because so many states are bright red, and because so many state-level anti-voting laws are now likely to go unchecked, there’s no guarantee that such a majority will materialize soon, but at some point one may. Ninety-six percent of sitting Democratic senators have already voted to change the rules. Unless Republicans can maintain power indefinitely, the days of the Senate’s 60-vote threshold are numbered.

The second way the filibuster could fall is far worse for Democrats: Republicans could regain full control of Washington and decide that the 60-vote threshold has outlived its usefulness. The last time the GOP held the House, White House, and Senate, in 2017, Republicans ignored President Donald Trump’s repeated calls to end the legislative filibuster. But if they regain control of Washington in 2024, the situation will be very different. Any newly elected Republican senators will belong to a party in which fealty to Trump—a filibuster opponent—is the most important plank. And even their long-serving colleagues may decide that, in a body governed mostly by precedent, Democrats have set a new one. Mitch McConnell or his successor can point to dozens of recent statements and speeches by their colleagues across the aisle arguing that the filibuster either should be ended entirely or ignored when a sufficiently crucial bill demands it.

This is especially true if Trump, or a Trumplike president, wants to rig elections nationwide. The overwhelming majority of Senate Democrats are now on the record articulating a principle: Protecting voting is an important enough priority that it is worth going around the filibuster in order to advance it. The same principle, repurposed under Donald Trump’s misleading definition of “election integrity,” could be used by Republicans to justify nationwide anti-voting laws as well. (Such arguments would be, of course, in bad faith. But that won’t prevent anyone from making them.)

Then there’s a third possibility: Someday we look back on this moment and realize that the filibuster that Manchin and Sinema were extolling, the guardrail against tyranny of the majority, was already dead—at least to Republicans. After all, during the Trump era, Republicans didn’t just pass massive upper-income tax cuts via budget reconciliation, which requires a simple majority vote. They also ended the filibuster for Supreme Court confirmations, installing the most conservative high-court majority in generations. That Court is now poised to accomplish a wish list of Republican legislative priorities—overturning Roe v. Wade, expanding gun rights, and hamstringing the government’s ability to issue regulations, among others—without having to find 60 votes for a single piece of legislation.

If Republicans regain the Senate, Democrats can filibuster conservative legislation. But that won’t matter much if filibuster-proof judges issue conservative rulings that have essentially the same effect. The full impact of the Court’s rightward turn has yet to be felt, but it’s possible that, thanks to these judges, the Senate’s rules are less a wall than a valve, facilitating conservative policies while blocking progressive ones. A real campaign to defend the filibuster would include restoring the 60-vote threshold for confirmations, and to her credit Sinema has suggested that she would be in favor of doing just that. But so far, just as she has failed to persuade many Democrats to join her in preserving the current 60-vote threshold, she has failed to persuade many Republicans to join her in trying to strengthen it.

Over the past year, reformers fought an uphill battle to convince senators that the chamber’s rules should be changed. But over that same time period, two of those senators set out on a no-less-quixotic quest: convincing their skeptical colleagues that the Senate rules should remain unchanged. They came up short. The filibuster is doomed.

The shame, and quite possibly the tragedy, is that Manchin and Sinema doomed voting rights along with it.