Tonight’s debate is going to focus in part on the Supreme Court, and for very good reason.

Barring some bombshell, the 2016 presidential election is over, and Hillary Clinton will beat Donald Trump. But control of the United States Senate is another matter. It is not at all clear who will win control of the Senate, and with Senate control comes the ability to confirm or block a Supreme Court appointment. And with a Supreme Court majority comes control of every important issue liberals and conservatives care about, from voting rights to the environment to abortion rights to gun rights. Let me take each of these points in turn.

Senate control means control of the Supreme Court. Republicans have been blocking the appointment of older, moderate D.C. Circuit Judge Merrick Garland for months, who President Obama nominated to replace Justice Scalia who died in February. They say it is to give the next president a chance to make the appointment, but it is really about preserving conservative control of the Supreme Court which has existed since the 1970s. Indeed, John McCain made waves this week when he suggested that Republicans in the Senate could block Hillary Clinton’s appointment to the Supreme Court for her entire term. (McCain’s office walked the claim back, but it is a pretty clear signal to conservatives to put all their efforts into keeping control of the Senate.) And now you have conservative Michael Stokes Paulson in the National Review that we should move to a Supreme Court of six Justices. No doubt about it: if Clinton becomes president and Republicans control the Senate, there will be a concerted effort to block ANY of her nominations to the Supreme Court.

But what about a Republican filibuster? Even if Democrats take narrow control of the Senate, the current Senate rules provide that it takes 60 affirmative votes to overcome a filibuster of a Supreme Court nominee. Democrats when they last controlled the Senate eliminated this rule for judicial appointees (and executive nominations generally) aside from the Supreme Court. There is no doubt in my mind that whenever Democrats or Republicans will need to kill the filibuster for Supreme Court nominees to get someone through, they will. Forget about comity in the Senate, forget about the question about whether this will ruin the special nature of the Senate. In this polarized time, that debate is over. The parties will do whatever they need to to get their nominees through. And there’s a pro-democracy argument to be made in favor of Democrats nuking the filibuster: the Senate is itself an undemocratic institution, where small states (such as Wyoming) get as much representation as big states (such as California or Texas). Majority rule without the filibuster in the Senate actually promotes democracy, especially because Democratic Senators represent more people than Republican Senators. The argument about the filibuster is essentially over. We are in an era of political hardball, and don’t expect Mitch McConnell to give a Clinton nominee even a hearing, and don’t expect Chuck Schumer to save the filibuster for Supreme Court nominees in the name of the Senate institution.

Multiple Supreme Court appointments in the next few years likely. I still expect if Clinton wins and Democrats retake the Senate, that the Republican Senate under McConnell will confirm Garland in the lame duck session of Congress (unless Obama withdraws the nomination, which I don’t expect). Why would he do this? Garland is older and more moderate than a likely Supreme Court nominee from Clinton. But even if that seat is filled, I expect Justices Ginsburg, Breyer, or both to go within the first two years of a Clinton presidency if there is a Democratic Senate in 2016. In 2018, there’s a very good chance Republicans will retake control of the Senate and block and further Supreme Court nominees. So there is a small window. The Supreme Court has had at least 5 (mostly) conservative Justices since the end of the Warren Court. From the 1970s on, we’ve had conservatives making decisions on the most important factors in American life. And now, all the conservatives on the Court are Republican-appointed and all the liberals are Democratic-appointed. This election may matter for up to a generation for control of the Supreme Court.

The Supreme Court is the most important civil rights issue of our time. I argued last year that “The future composition of the Supreme Court is the most important civil rights cause of our time. It is more important than racial justice, marriage equality, voting rights, money in politics, abortion rights, gun rights, or managing climate change. It matters more because the ability to move forward in these other civil rights struggles depends first and foremost upon control of the Court. And control for the next generation is about to be up for grabs, likely in the next presidential election, a point many on the right but few on the left seem to have recognized.” This is the moment that this all matters. And it all comes down to the Senate.