If and when Republicans refuse to allow any debate of the Democrats’ voting rights legislation on Tuesday, there will be a hidden silver lining: It will finally force the Senate to engage in the grand argument over the filibuster that many of its denizens have ducked for so long.

As one of the last Democratic holdouts against filibuster reform, Sen. Kyrsten Sinema (D-Ariz.) is making big news with an op-ed in The Post laying out her rationale. Some of its central pronouncements have already been debunked: Despite her claims otherwise, the filibuster does not facilitate moderation or bipartisan cooperation.

But there’s an even more fundamental flaw in Sinema’s argument: Defending democracy and the filibuster simultaneously, in the terms that Sinema herself employs, is simply incoherent to its core.

Sinema’s own treatment of these questions inadvertently serves to reveal that a choice must inevitably be made between the two — and that Sinema is choosing the filibuster over defending democracy.

The core of Sinema’s argument is that “we will lose much more than we gain” from ending the filibuster. Sinema opposes doing this even for the narrow purpose of passing the sweeping voting rights reforms that already passed the House:

To those who want to eliminate the legislative filibuster to pass the For the People Act (voting-rights legislation I support and have co-sponsored), I would ask: Would it be good for our country if we did, only to see that legislation rescinded a few years from now and replaced by a nationwide voter-ID law or restrictions on voting by mail in federal elections, over the objections of the minority?

That truly is frightful. Imagine a world in which legislative majorities could pass voting restrictions over the objections of minorities!

Oh, wait, we already live in that world. In state after state after state, voting restrictions of all kinds are being passed into law by Republican-controlled legislative majorities, over the objections of minorities. Crucially, this is happening almost exclusively on partisan lines.

Those include exactly the restrictions that Sinema alludes to: stricter voter ID laws and efforts to curb vote by mail, as well as other anti-majoritarian tactics such as extreme gerrymanders. In short, the rules of political competition are already being rewritten by one party all over the country, with an eye toward entrenching partisan advantage and minority rule.

Sinema, of course, is lamenting the possibility that if we did away with the filibuster, a Republican-controlled Congress might more easily pass such measures on a national level, whereas right now, this is happening everywhere on the state level.

But this actually throws the underlying incoherence of Sinema’s argument into even sharper relief. Sinema admits that these types of voting restrictions are threats to democracy, but without forthrightly acknowledging that they are already being passed everywhere by state legislative majorities along party lines.

That’s because seriously grappling with that reigning reality would render Sinema’s stance publicly untenable. Sinema says she supports the For the People Act, which means she generally supports using federal legislation to check such abuses. Yet Sinema simultaneously downplays the very existence of those abuses.

Now contrast this with Sen. Jon Tester (D-Mont.), who told NPR that he’s open to ending the filibuster to pass new federal electoral standards precisely because Republican-controlled state legislatures are rolling back voting access and entrenching anti-democratic practices everywhere.

If Sinema were to forthrightly acknowledge those abuses, it would show that the filibuster enables a starkly unbalanced situation: While legislative majorities pass dramatic anti-democratic measures everywhere on the state level, this can only be checked on the federal level by a legislative supermajority.

Sinema could deal with this imbalance forthrightly if she chose. She could try to argue that even though the filibuster will allow those state legislatures to run rampant for the foreseeable future, the damage done to democracy by ending the filibuster, even if it’s just to place a check on those tactics, would nonetheless outpace the damage done to it by the tactics themselves.

But Sinema doesn’t even attempt that argument. Sinema claims that “we have more to lose than gain” from ending the filibuster, but without admitting to what we actually would gain from ending it in this context — a check on democratic backsliding and the slow but steady entrenchment of minority rule.

That this democratic deterioration is upon us is not solely a partisan view. It’s the opinion of hundreds of leading democracy scholars and political scientists, both of whom recently signed statements of principles warning that we are at risk of exactly that.

In the end, the real reason Sinema can’t admit to what we would gain from ending the filibuster, and what we might lose by keeping it, is this: It would be tantamount to admitting that her position risks consigning us to that very fate.

On top of all this, Sinema won’t even entertain ending the filibuster to pass more modest checks. Sen. Joe Manchin III (D-W.Va.) has offered a good-faith effort to compromise with Republicans that includes a mild form of voter ID, expanded voting access and curbs on partisan gerrymanders. Yet Sinema and Manchin will apparently allow it to be filibustered, too.

It’s too bad Sinema will not forthrightly engage with the actual trade-offs at play in this debate. That she is playing this slippery game while piously claiming to be a great defender of democracy only makes it all the more galling.

Read more: