Sen. Elizabeth Warren (D-MA) thinks Democrats should end the filibuster if they regain the majority in the US Senate, and pass legislation by majority rule.

“When Democrats next have power, we should be bold and clear: We’re done with two sets of rules — one for the Republicans and one for the Democrats,” Warren says in advance text of a Friday speech to the National Action Network obtained by CNN. “And that means when Democrats have the White House again, if Mitch McConnell tries to do what he did to President Obama and puts small-minded partisanship ahead of solving the massive problems facing this country, then we should get rid of the filibuster.”

Warren is, of course, running for president and doubtless envisions herself as leading this charge from the White House. The Senate, however, makes its own rules, and a majority of senators could vote to change the rules and allow majority votes to prevail. If Democrats fare well in 2020, a rule change would greatly increase the likelihood that some of these big progressive ideas could come to fruition. But top Democrats are skeptical.

“We should not be doing anything to mess with the strength of the filibuster,” says Sen. Cory Booker (D-NJ).

Most presidential candidates in the Senate are with Booker. Bernie Sanders (I-VT) says he’s “not crazy about getting rid of the filibuster.” His plan for Senate reform is statehood for the District of Columbia, which he thinks can be done because “I hope my Republican colleagues do the right thing.”

Sen. Kamala Harris (D-CA) is “conflicted.” And Sen. Kirsten Gillibrand (D-NY) is concerned about the risks to being in the minority. “Having just lived through being in the minority,” she explains, “I just want to think long and hard about it.”

Candidates not in the Senate, by contrast, are more inclined to agree with Warren. South Bend Mayor Pete Buttigieg is all for scrapping it, as is Washington Gov. Jay Inslee.

This debate is important because there’s no way almost anything the candidates are promising to do will happen unless the filibuster is lifted.

It’s up to the Senate to change its rules, not the president — Barack Obama’s calls for filibuster reform didn’t work, and neither have Donald Trump’s — and most of the candidates running are going to be back in the Senate after 2020. They show little appetite for reform.

Progressive politics right now is very focused on broad ideological visions. It hasn’t grappled with the reality that progressives are at a massive disadvantage in the upper chamber of Congress and no bold idea will make it through without a change.

A brief history of the filibuster

Fans of the filibuster often describe it as a noble and longstanding Senate tradition, evoking the image of Jimmy Stewart speaking for 25 hours straight to fight corruption in the movies. But the practice actually has a mostly sordid history. And its current usage serves as a de facto requirement that all bills clear a supermajority threshold.

In its earliest days, the US Senate lacked any procedural mechanism for forcing the end of debate on an issue. This was understood as a matter of collegiality in what was at the time a very small legislative body, and not as a requirement that legislation be unanimous. There were a handful of filibusters over the course of the 19th century (North Carolina Sen. William King organized an important 1841 filibuster of legislation to reauthorize the charter of the Second Bank of the United States), but in general, legislation passed by majority rule.

Things changed in 1917. Near the height of World War I, Germany announced a policy that its submarines would enforce a blockade of Britain-bound shipping by sinking any merchant vessels heading for the British Isles. In response, Woodrow Wilson and most members of Congress supported legislation that would arm American merchant ships. Sen. George Norris of Nebraska along with 11 colleagues filibustered the bill, and in response, Wilson urged the Senate to adopt a rule allowing for a supermajority of 67 senators to kill a filibuster.

This allowed Wilson’s wartime legislation to pass, but somewhat ironically, limiting filibusters served to somewhat normalize them, and it became routine for a Southern-based minority of senators to filibuster civil rights legislation.

Over the civil rights battles of the 1950s and ’60s, filibustering rules were tweaked several times until the modern filibuster rule emerged in the 1970s. The key features of the modern system are that it requires 60 affirmative votes to end debate on a topic but also that the Senate can simply move on to other issues without having formally invoked cloture on earlier issues. This turned filibustering into a less spectacular event than it had previously been — to filibuster a bill no longer meant holding up all bills — which in practice has served over time to encourage senators to do it more and more frequently.

As recently as the George W. Bush administration, however, it was still the case that not everything was filibustered. Both his 2003 Medicare reform bill and the nomination of Samuel Alito to the Supreme Court passed with more than 50 but fewer than 60 votes, though Democrats did also take the previously unprecedented step of filibustering federal appeals court nominees.

During the political standoff over these appeals court filibusters, some of us argued that Democrats should take advantage of Republican frustration to strike a high-minded compromise and return the Senate to the principle of majority rule.

But Democrats did not take that advice, only to find a few years later when Barack Obama was in office that Republicans were now holding everything to a 60-vote threshold. Constant filibustering shrank the size of the stimulus (consigning millions of people to years of additional unemployment), compromised the design of the Affordable Care Act and the Dodd-Frank Act, and doomed any effort to legislate on climate change or immigration reform.

Later, Republican filibustering of Obama’s nominees got so out of control that Senate Democrats felt compelled to change the rules and make filibustering of nominees impossible.

Under Trump, Republicans have taken advantage of that new rule set to get judges confirmed at a rapid pace. But Democratic filibusters have impeded Republican legislating, ensuring that even before Democrats took House in the 2018 midterms, the GOP could not pass legislation to build a wall or cut legal immigration.

The filibuster is probably bad for the left

Which party the filibuster advantages or disadvantages depends on the current state of politics — in 2005-2006, filibustering frustrated Republicans; in 2009-2010, it frustrated Democrats; in 2017-2018, Donald Trump issued the clearest call for filibuster abolition that we’ve seen from any president.

A separate question is whether a shift to majority rule would advantage one side over the other systematically over the long haul.

There is, of course, no real way to prove this. But historically, anti-filibuster sentiment has mostly come from the left. Even though policy obviously swings back and forth over time, there does tend to be a ratchet effect. The fight for women’s suffrage was long and difficult, but once women had the vote, taking it away was essentially impossible. A broadly similar dynamic tends to play out with social welfare programs as well.

UC Berkeley political scientist Paul Pierson explained in his 1994 book Dismantling the Welfare State? and his follow-up 1996 paper “The New Politics of the Welfare State” (and a 2017 interview with Vox) that even very successful conservative politicians like Ronald Reagan and Margaret Thatcher generally fail to take away major social benefits once they’ve been created. Pierson argues that social programs create a new politics, and in particular build a constituency of people benefiting from the programs that is politically powerful and can resist efforts to dismantle them.

This is obviously not an ironclad law of nature. But the fact that Bush failed to privatize Social Security and Trump failed to repeal the Affordable Care Act tends to further support Pierson’s original analysis of Thatcher and Reagan. Note in particular that Bush’s Social Security plans never managed to pass the House, while Trump ACA repeal bills were eligible for a procedural maneuver that would have needed only a simple majority; in neither case did the filibuster save the welfare state’s bacon.

It’s very hard to create big new programs, but once they’re in place, they are hard to take away. There is, for example, vociferous disagreement about the political viability of a Big Bang switch away from the current US health insurance patchwork to a uniform single-payer system. But nobody thinks that if a single-payer system existed, it would be remotely viable to try to switch back to the current pastiche. Similarly, if you passed a law making it easier to form labor unions, that would lead to more unionized workers, which would make it harder to pass new anti-union laws.

Of course, even if you accept this logic, it’s still the case that some important specific progressive causes — the legality of late-term abortions or the continued existence of the diversity visa lottery — could be imperiled by ending filibusters.

More fundamentally, however, the filibuster’s existence is convenient for actual senators.

Supermajority rule makes life easier for senators

In his classic book Congress: The Electoral Connection, Yale political scientist David Mayhew makes the point that members of Congress are generally rewarded for “position-taking” rather than for achieving results.

And while the filibuster makes it harder to achieve results, precisely for that reason, it makes position-taking easier. A Democratic senator facing pressure from activists to raise the federal minimum wage to $15 an hour might worry that his read of the economics literature is much more supportive of something like a $12 wage floor. But coming out for $12 would disappoint activists without meaningfully appeasing employer groups who oppose any increase whatsoever. The good news for our conflicted senator is that since it would take 60 votes for a bill to pass, there’s very little need to worry that even unanimous Democratic support for $15 an hour is going to produce a $15-an-hour minimum wage anytime soon.

If you decide that you want to side with the activists, in other words, you can just side with the activists and not worry too much about the details. A senator can even take a position in favor of some sweeping piece of legislation and then quietly reassure interest group opponents that everyone knows this isn’t getting 60 votes and really just represents an opening bid.

Senators in purple states, meanwhile, often enjoy the ability to avoid taking clear positions on issues. Since many areas of policy can, in practice, only be legislated on via bipartisan deals, it’s usually possible for a member to remain ambiguous whenever that seems most suitable.

Reform happens on the rare occasions when the imperative to actually make policy outweighs senators’ preference for position-taking. Wartime exigency in 1917 was such an example. The GOP using filibusters of nominations to render whole federal agencies inoperable was another. Democrats saying they wouldn’t confirm Neil Gorsuch to the Supreme Court simply because they didn’t like his jurisprudence was yet another.

Had Senate Republicans blocked any fiscal stimulus move in 2009, that might have prompted filibuster reform. But instead, Susan Collins and Olympia Snowe agreed to back a somewhat scaled-down package. Later, GOP filibusters of immigration and climate legislation were frustrating to progressives.

But fundamentally, the fact that bills on this topic would have to be bipartisan to pass was exactly what most Democratic members found appealing about the filibuster rule.

Democrats have big ideas but no plan

Rightly or wrongly, Democrats headed into the Obama years with the expectation that they’d be able to do to a lot of substantive legislation on a bipartisan basis.

The Affordable Care Act drew inspiration from several ideas that had attracted Republican support in the past, and during the Bush years, both carbon emissions reduction bills and comprehensive immigration reform bills had received support from a non-trivial minority of GOP legislators. Similarly, for years his administration aspired to achieve some kind of bipartisan “grand bargain” on the long-term budget deficit that would pair tax increases on the wealthy with cuts to Social Security and Medicare spending.

This was all proven mostly false by the end of Obama’s first term. Still, Obama harbored hope that securing reelection would “break the fever” and unlock the doors to bipartisan cooperation. For a brief moment in 2013, it even seemed like that might be true, until conservative opposition torpedoed a once-promising bipartisan immigration reform bill.

Today’s Democrats no longer frame proposals around bipartisan legislative strategies that nobody believes will work. But Warren’s words aside, there’s also no indication that Democratic senators — including many of the authors of the main ambitious proposals that have dominated the policy debate — are taking any steps to move the Senate to a majority rules basis. Nor do they seem content to limit aspirations to the kind of changes that could qualify for the budget reconciliation loophole. There is, however, no realistic chance that Democrats are going to pick up 13 Senate seats in 2020.

Indeed, even taking a majority would be a stretch.

Every Senate map is bad for Democrats

A perennial cliché of 2018 midterms coverage was that Democrats faced a bad “map” in the Senate, with many of their incumbents up for reelection, often in tough states.

And, indeed, the map was so bad that even in the context of the party winning a huge landslide in the House popular vote, they actually lost Senate seats. The 2020 map will be, relative to 2018, considerably kinder.

There is one highly vulnerable Democratic incumbent (Doug Jones in Alabama) and one highly vulnerable Republican (Cory Gardner in Colorado), plus a handful of plausible Democratic pickups in Arizona, Georgia, Iowa, North Carolina, Maine, and maybe Texas, with really nothing plausibly on the board for the GOP.

A more pessimistic way of looking at it, however, would be this. In 2016, Hillary Clinton won the national popular vote by a healthy 2 percentage points. Nevertheless, she only carried 20 states out of 50. Three of those states — Pennsylvania, Michigan, and Wisconsin — were very close, so a slight improvement on her 2-point win would get Democrats to 23. Then there’s Florida, which she lost by 1.2 points, and North Carolina, which she lost by 3.7 points.

Assuming a uniform swing, in other words, a Democratic presidential candidate would need to win the national popular vote by almost 6 percentage points in order to carry half the states. That’s not impossible to pull off — Obama did it in 2008, Bill Clinton did in 1996, and George H.W. Bush did in 1988 — but it’s certainly rare. And this means Democrats are going to perennially struggle to obtain a Senate majority. It’s not out of the question that Democrats will hold 50 seats after 2020, but to get them, they’ll need to win multiple races in states that Clinton lost by 4 to 5 points and knock off a popular moderate incumbent in Maine — winning a majority of votes nationwide won’t be good enough.

The problem, to a first approximation, is that America’s largest states — California, Texas, New York, and Florida — all have significantly more non-Hispanic whites than the national average. That ends up meaning that most states are whiter than the national average, meaning white voters — and, as it turns out, specifically rural and less-educated white voters — are significantly overrepresented in the Senate map.

Filibuster reform could be a plan

This Senate disadvantage arguably strengthens the progressive case for keeping the filibuster, since if you expect the GOP to hold the majority most of the time, then majority rule voting could only empower Republicans. But there are two offsetting considerations.

One is that the underrepresentation of voters of color in the Senate could be partially rectified by turning DC and Puerto Rico into states, but to do that, you’d need to overcome GOP filibusters. The other is that arguably filibustering itself — by making it hard to pass legislation — encourages politics to focus on the hazy culture war topics that allow Republicans to run up the score with rural white voters.

Democrats’ pitch to working-class white voters is that they have plans to help them in concrete, material ways. But to deliver that help — whether it’s on health care, rural broadband, infrastructure, or anything else — Democrats need to be able to legislate.

If the reality of politics is that actual policy change is going to be extraordinarily rare and normally take the form of bipartisan deals negotiated behind closed doors, by contrast, then it arguably does make sense for voters to ignore their specific material interests and vote on the basis of hot-button symbolism instead.

In a majority-rule Senate, it would make sense to ask voters to elect senators — and a president — who will deliver Social Security expansion or revise antitrust law. But if the reality is that none of this stuff is actually on the table, then why not vote to signal your disapproval of Colin Kaepernick or the excesses of campus political correctness?

But so far, there is no indication that Senate Democrats as a group are taking the possibility of filibuster reform even remotely seriously. Even members who were vocal and active on the issue in the mid-Obama years have largely gone dormant.

That doesn’t change the fact that there are very real stakes in the 2020 presidential campaign. But it does mean those stakes relate more to foreign policy and executive branch appointments than they do to the big-picture legislative topics that have dominated the discussion thus far.