If the leaked draft Supreme Court opinion overturning Roe v. Wade becomes finalized, the prospects for restoring national abortion rights protections in the near term are grim.

The medium- and longer-term prospects, though, are … still grim, but slightly less so.

Justice Samuel Alito’s draft opinion would lift the Court’s prohibition of state laws banning abortion, ending a status quo that has held for nearly 50 years. The Court’s conservative majority looks entrenched, for now. But the political situation can change over time, and in unexpected ways, though it could take years or even decades for the right circumstances to arise.

There are three basic scenarios by which Roe’s protections could be restored — none of which are particularly likely, but none of which are outright impossible either.

One goes through the Supreme Court: Future liberal appointees could just, well, put Roe back. A second goes through Congress: A bigger Democratic majority could either overcome the filibuster (if they have 60 votes) or vote to eliminate it with a majority, opening the way to codify Roe in law or even pack the courts.

Both paths require Democrats to win more elections. Appointing any justice will likely require the presidency and Senate control. Passing new laws would require a bigger Senate majority and holding the House as well.

It may sound banal to say, as President Joe Biden has, that the best hope abortion rights supporters have for restoring Roe’s protections is keeping Democrats in control of the presidency and Congress, with as big majorities as possible. But it’s pretty clearly true.

It’s also easier said than done. Democrats’ current voter coalition is disadvantaged in the Electoral College and the Senate map. And if new Court appointments or new laws restore Roe, the next time Republicans regain power, they’d have the same tools — they could appoint new justices or even ban abortion nationally if the filibuster is gone.

A third scenario, though, would involve a change in the Republican Party. The GOP could calculate, due to a public opinion backlash or electoral defeats, that they need to moderate on abortion.

That’s certainly not going to happen in the foreseeable future; it would have to be a long-term transformation. But it’s really the only chance for national abortion protections to be durably reestablished, because their seeming safety over the past 50 years was always illusory so long as the GOP was gunning for them.

Scenario 1: Fill naturally occurring Court vacancies

Roe is set to be overturned by a majority of five Supreme Court justices, and it could be put back by another majority. To get there, Democrats would have to replace at least one, and probably two, conservative justices with liberal ones.

The problem is that conservative justices will try not to retire while Democrats are in power. So this path would rely partly on chance (when justices happen to die or become otherwise unable to serve). Yes, these are the grim calculations that the Supreme Court’s lifetime appointments incentivize.

But it’s not entirely chance. It’s also about electoral performance — who holds the presidency and the Senate when justices die or step down. For instance, Thurgood Marshall, a liberal justice appointed in 1967, had hoped to be replaced by a Democratic president. But Republicans won the 1980, 1984, and 1988 elections, he decided his health couldn’t hold out any longer, and in 1991 he was replaced by Justice Clarence Thomas.

The more a party wins, the better the odds an unexpected Supreme Court vacancy will arise while they’re in power. This means holding the presidency, and likely nowadays it means holding the Senate too — Senate Majority Leader Mitch McConnell’s Republican majority blocked President Barack Obama from replacing the late Justice Antonin Scalia.

Republicans assembled their anti-Roe majority by waiting for these vacancies to arise and acting aggressively when they did. They got Neil Gorsuch confirmed instead of Merrick Garland, made sure Brett Kavanaugh was confirmed before the 2018 midterms could have lost them the Senate, and voted up Amy Coney Barrett just over a month after Justice Ruth Bader Ginsburg died.

But this is hardly a quick fix — it took nearly 50 years for Republicans to get this five-vote anti-Roe bloc. So Democrats could be waiting a while, too. After Justice Stephen Breyer steps down this summer, there will be no more octogenarians on the Court, and its oldest justices will be Clarence Thomas and Samuel Alito, who are 73 and 72, respectively.

Democrats can maximize their chances of having power at the right time by holding the presidency and Senate as long as possible, but there’s no guarantee the opportunities will arise any time soon. And the more elections Republicans win — allowing them to replenish their aging conservative justices with younger ones — the further these prospects will recede.

Still, things can change quickly. As late as early November 2016, it seemed plausible, and perhaps even likely, that Roe was safe and liberals were on the cusp of their first outright Supreme Court majority in decades. But Trump won, Republicans held the Senate, and Ginsburg died, so here we are.

Scenario 2: Act through Congress by abolishing the filibuster

So rather than simply waiting, perhaps forever, the other path is for Democrats to act through Congress by passing new laws. This could be an abortion-specific law codifying Roe’s protections (though that would have to survive this Supreme Court). Or, congressional Democrats could pack the Supreme Court, as some progressives want — expanding its size and filling new slots with liberals.

Democrats won’t be able to do either of these right away, though, for the same reason: the Senate’s filibuster rule, and moderate Sens. Joe Manchin and Kyrsten Sinema’s insistence on keeping that rule.

It takes 60 votes to advance legislation through the Senate unless it’s a budgetary bill, which neither of these proposals would be. If Democrats managed to regain a 60-vote Senate majority, as they briefly had in 2009 and early 2010, they could overcome the filibuster and pass new laws. (Probably 61 would be needed if Manchin, who is likely not a reliable vote on measures protecting abortion rights, is still around.) But it would be tremendously difficult to win so many seats, especially since the party faces a structural disadvantage in the Senate map.

Alternatively, a smaller Democratic majority could deploy what’s known as the “nuclear option” to change Senate rules and get rid of the filibuster with just their majority (50 votes plus the vice president). But this current Congress has failed to get that done — Manchin and Sinema have refused pressures to do this since their party took power.

Theoretically, if Democrats managed to expand their majority by two more Senate seats, they could move forward with a rules change — unless another moderate suddenly comes down with a case of cold feet. Alternatively, if a future Republican Senate abolishes the filibuster, Democrats would be able to pass abortion protections next time they’re in power.

Yet if the filibuster is abolished by either party, Republicans would be able to pass laws with a simple majority when they’re in power, too. They could at the very least reverse any Democratic law establishing abortion protections, and at most try to ban abortion nationwide. If Democrats expand the court, the GOP could expand it further.

So congressional action wouldn’t result in a durable restoration of Roe unless Democrats can manage to keep holding onto Congress. That will prove quite difficult, particularly in the Senate. Democrats have the narrowest possible Senate majority right now, but their voter coalition is not well distributed for the Senate map, where they could well fall into a deep disadvantage in the coming years. Again, their way to maximize their chances of success is by winning more of these elections, but that’s quite difficult.

Scenario 3: Shift the GOP’s position by winning the war of public opinion

Though abortion rights activists were well aware for years of the danger Roe was in, less-engaged American liberals may have simply taken it for granted, assuming it would be around forever. It had survived for so long, after all, so it would probably keep surviving, right?

But this safety was an illusion because abortion rights had never won the truly widespread public support it would take to entrench them nationally. Many conservatives continued to argue that abortion was deeply wrong and Roe should be overturned, and one of the country’s two major political parties has been committed to that viewpoint for decades.

Indeed, Roe was very nearly overturned three decades ago, in 1992, but conservatives on the Court fell one vote short of a majority to do so because moderate Republican-appointed justices voted with their more liberal colleagues. Anti-abortion activists then spent the next three decades trying to make sure that would never happen again. Their success in creating an anti-Roe Court majority certainly wasn’t inevitable — it took a very long time and required a good deal of good luck — but they do now seem to have achieved it.

The reality, then, is that even if Democrats do somehow manage to restore Roe’s protections nationally, all that would be subject to reversal the next time Republicans hold power. The Court could swing back and forth based on new appointments. Or, if Democrats eliminate the filibuster and codify Roe or pack the Court, Republicans could reverse those measures or enact further-right measures (say, with a national abortion ban) next time they’re in charge.

The only way to pull out of this spiral would be if anti-abortion activists lose their hold on the Republican Party, and probably on the Republican electorate too. Perhaps a national backlash against the GOP for overreaching on abortion will materialize, and they’ll feel compelled to moderate their position or lose power. Or perhaps even the red-state public, once abortion restrictions are implemented and their effects become clear, will grow convinced they actually aren’t desirable.

At the moment, such a scenario seems far-fetched, bordering on impossible. And maybe it is. But in the long term, that’s what would be needed to entrench abortion protections nationally. If a public opinion shift doesn’t happen, Roe protections, even if they are restored, would never truly be safe.