After several months of campaigning for the Democratic presidential nomination, Elizabeth Warren and Bernie Sanders are playing very nice with each other. But the rest of us are starting to debate the differences between the two more sharply, whether thoughtfully or absurdly and dishonestly.

It should be clear from reading Jacobin ’s coverage of Elizabeth Warren that she is not a corporate shill, nor an enemy of working people. She’s an actual progressive Democrat, proposing real reforms. But she is a progressive Democrat at a time when the bar has been raised (finally, thankfully) beyond progressivism.

Just four years ago, both Sanders and Warren were political outliers, and no mainstream Democrat would touch “fringe” issues like Medicare for All or a Green New Deal with a ten-foot pole. Ten years ago, vague promises of “Yes, we can” seemed enough to win hearts and minds and then sell us more of the same old “No, we can’t.” Twenty years ago, Democratic candidates refused to even admit they were “liberals,” let alone radicals or socialists.

There has been a sea change in politics. It’s been building over these past two decades alongside grotesque economic polarization, endless wars, and racist scapegoating. And it has accelerated profoundly in the last few years.

It is undeniably good for the Left — and a sign of the leftward leaning, radicalizing times that we live in — that Warren and Sanders have dominated the political debates and mainstream discussions during the primary season. Bernie’s signature “Medicare for All” proposal went from a pipe dream of leftists to the yardstick against which other platforms are evaluated, seemingly overnight. To watch Bernie and Warren team up in primary debates to destroy the pro–private insurance arguments of the moderate Democrats on national television is like a dream come true.

Yet denying that there are differences between Warren and Sanders, or that they matter for the future of this country and the building of left movements beyond 2020, makes no sense either.

On the policies themselves, Bernie’s solutions are more systemic and far-reaching. Warren’s and Sanders’s relationships to the Democratic Party and to Democratic Party donors are indicative of contrasting approaches to the political elite. And their bases of support demonstrate very unequal capacities to build the kind of movements we need on the ground to take on the billionaire class.

To raise all this is not to pettily score points for one candidate nor to nitpick the weaknesses of another, but because it actually matters which direction we go in. There are two reasons why: 2020, and 2021.

Next year’s presidential race has the potential to depart radically from the norm. The pattern of election cycles has been, in all but the most exceptional circumstances, that Democratic politicians come in with abysmally low, vague promises. We are expected to respond with “please and thank you” in the name of pragmatism and defeating the terrifyingly worse other guy.

Once the election is over, the best-case scenario is that the Democrat wins, but the vague promises disappear about as soon as he is sworn in; the worst-case scenario is that the terrifying guy wins because nobody could get excited about the “please and thank yous.”

Yet during this election cycle, Bernie is putting forward radical overhauls of nearly every institution and industry in the country. In many cases, his proposals are further to the left than even movements on the ground have called for.

Warren is certainly a breath of fresh air over the “please and thank you” candidates, but she falls short of calling for systemic transformation. She is, in her words, a “capitalist to her bones” and a believer in the ultimate good of the markets. Many of her proposals leave the door open to further compromise down the line — such as the claim that Medicare for All is a good “framework,” with little by way of concrete commitment as to whether private insurance will be eliminated outright and whether health-care services will be free. And her campaign has consciously cultivated her reputation as a more palatable liberal alternative to Bernie, one that even Brookings Institution fellows can swallow.

“It’s not as though [Warren is] content to thunder against the evildoers like an Old Testament prophet. That’s much more his mode,” said William Galston, a senior fellow at the Brookings Institution and former domestic policy adviser to President Bill Clinton. “Sanders sees [his campaign] as a revolutionary mass movement to upset the established order. While Senator Warren is obviously very dissatisfied with the status quo, she describes her campaign in very different terms and terms that I think are less scary.”

Sanders has raised the bar for what we can demand; socialists aren’t going to preemptively lower it. And on issue after issue, to support Warren’s position is to lower the bar. This is the difference between “single payer, no cost health care” versus a vague, bare-minimum promise that “nobody goes broke” because of their health-care bills. The environment is ripe for a mass audience to coalesce around more robust positions, and everyone who believes in winning a better world should encourage and advance this development.

More important, we should utilize Bernie’s campaign slogan, “Not me, us,” not as merely a pithy catchphrase, but as a call to organize. This brings us to 2021 and beyond.

The reality is that neither Warren’s nor Sanders’s policies stand a chance of passing, much less sticking, without a mass base on the ground that can fight for them. The solution is not more wonkish or “pragmatic” plans, but fighting movements. As Connor Kilpatrick and Bhaskar Sunkara recently argued:

[I]n 2019, with the balance of class forces so lopsided, it’s less a question of policy papers and more a question of armies: the ruling class has theirs — total control over the economy and the state (not to mention the literal army), with only a vaguely disgusted public and a historically weak labor movement to oppose them. For even the slightest chance of tipping the balance, the have-nots will need an army of their own to make the impossible once again possible.

Despite the weaknesses of the Left, we have a unique opportunity to embolden and organize movements today. A deepening radicalization, a growing “militant minority” within workplaces, an inspiring teachers’ strike wave, and the unmistakable popularity of a socialist running for president. along with his class struggle platform, makes for a rare historical opportunity.

Bernie is uniquely positioned to help us do so. Every time he opens his mouth, he clarifies who the enemy is — the billionaire class, the health insurance and pharmaceutical industries, fossil fuel companies, Wall Street, the military-industrial complex — and names capitalism as the problem to boot. He has put words to deeds by sending supporters to picket lines. His campaign in 2016 had the effect of giving confidence to burgeoning movements, from the Green New Deal to the teachers’ strike wave. In 2019 and 2020, his even more radical positions on everything from housing to racial justice will continue to do so.

Bernie’s whole orientation has been to explicitly argue that no real change can come from the White House alone. “Not me, us” is an admission of this reality, and his promise to become the “organizer-in-chief” can provide movements and the Left with a national profile for radical ideas, along with the organizing infrastructure that comes out of the campaign itself. As he put it:

In my view, there will never be any real change in this country unless there is a political revolution. And that means that millions of people have got to stand up and take on the corporate interests, the billionaire class, the 1 percent and tell them that in this country our economy and our government belong to all of us and not just wealthy campaign contributors.

This is a moment the Left has been waiting for a long time. It hasn’t come in the form many expected, but it’s here nonetheless. In this context, it matters how far we set our political horizons, and how we approach getting there. More than any other figure in recent history can be said to have done so, Bernie is expanding our horizons. Rather than policies or plans alone, he is calling on social movements to overturn the entire state of affairs. For all her progressive policy ideas, Elizabeth Warren isn’t. If we’re serious about changing the world, that difference matters.