Every few days, a new Democratic presidential candidate joins the race promising a ground-up rebuild of the health care system, a Green New Deal to address climate change, or a sweeping overhaul of the immigration system to represent something more humane. These are ideas that are unlikely to attract meaningful Republican support. And so, unless Democrats can get 60 seats in the Senate, something that certainly won’t happen even in their rosiest 2020 forecast, they would likely need to eliminate the filibuster—the rule that allows 41 senators to block legislation—to achieve most of them.

Under the so-called “nuclear option,” which Democratic and Republican Senate majorities have used in recent years to eliminate filibusters on presidential nominees, the legislative filibuster could be “nuked” with a simple majority of Senate votes. This is exactly what many progressive supporters of major health care, climate, immigration, and gun control legislation want Senate Democrats to do if they can unify control of the government in 2020. But it’s almost impossible to see Senate Democrats doing it. Their margin in the Senate, even if they were able to squeak out a majority, would be razor-thin, and dozens of Democrats have gone on the record in the past couple of years supporting the legislative filibuster. Even if only a few of them are telling the truth, that would be enough to preserve the filibuster and sharply limit the scope of what a Democratic House, Senate, and presidency could achieve relative to their outsized campaign platforms. For all the talk of killing the thing, press ever so gently on the Senate Democratic caucus, and strident defenses of the legislative filibuster gush out.