Yesterday, the New York Times reported a fact that’s been circulating in quieter corners of the internet for a while: Elizabeth Warren is partially funding her presidential campaign with money raised from wealthy megadonors throughout 2018.

When she announced her presidential campaign this year, Warren promised to eschew the traditional top-dollar donor circuit. But, as Shane Goldmacher points out, “Last winter and spring, she transferred $10.4 million in leftover funds from her 2018 Senate campaign to underwrite her 2020 run, a portion of which was raised from the same donor class she is now running against.”

Her campaign treasurer, meanwhile, is “a key benefactor and rainmaker for Democratic political committees” with a fat Rolodex of wealthy liberal super-PAC donors. Add to this the fact that Warren has stated clearly that she’ll drop her big-donor ban during the general election if she wins the primary, and a picture starts to emerge of a candidate who is not particularly committed to keeping the donor class at arm’s length.

Warren was schmoozing in Silicon Valley and Martha’s Vineyard right up until her reelection to the Senate in November 2018. By her own account, she intends to revive the practice if she wins the nomination in July 2020. Explaining why, she told the Young Turks, “Look, I do not believe in unilateral disarmament. We need to win. We need to win in 2020. When we hit 2020 and we’re in a race with Donald Trump . . . we got to be all in.”

All told, Warren has promised a less than two-year abstention period from courting the wealthy.

If Warren’s heart’s not really in it, why make the promise at all? The answer has everything to do with Bernie Sanders, who has risen to prominence by saying things like, “I don’t represent large corporations and I don’t want their money.”

Every politician who wants to be seen as progressive has had to adjust their strategy since Sanders’s 2016 primary run. That year, when Sanders pointedly ran a surprisingly successful insurgent campaign without cozying up to elites, he went out of his way to imbue his unorthodox fundraising with political meaning. By openly refusing to rub shoulders with liberal megadonors, he singlehandedly transformed the Democratic Party’s most reliable fundraising strategy — something taken for granted and given tacit approval for decades — into a political liability.

This time around, candidates have been forced to make overtures to the idea of a “grassroots-funded” campaign like never before. Otherwise, they risk fomenting doubt about their commitment to fighting for working-class people against the corporate class that suppresses wages, lobbies for tax cuts, and destroys the planet for profit. This is especially perilous terrain for Warren, a longtime crusader against corporate excess who nevertheless extols the virtues of well-regulated capitalist markets. Without Sanders in the mix, her progressive bona fides would be ironclad, but with him around, she needs to guard them carefully.

Warren’s campaign strategy has been to promote the idea that she’s every bit as progressive as Sanders, only with more fleshed-out plans. To shore up that impression, she’s smartly opted to forego big money for the time being. But laudable though the decision is, “for the time being” won’t cut it. To make lasting change in working-class people’s lives, we need leaders who aren’t afraid to make enemies of capitalists — to be feared by them, not just for a short stint, but for life.

The Democratic Party has always been a cross-class institution. Its base is majority working-class, while its figureheads and functionaries have largely come from the elite and bent over backward to protect capitalist interests. In exchange for that protection, the party has received a steady influx of capitalist dollars to sustain its electoral operations. While some industries (tobacco, fossil fuels, defense) reliably back Republicans, others (finance, real estate, tech, entertainment, health care) tend to tilt to the Democrats, and the Democrats like it that way.

The result is that the Democratic Party speaks out of both sides of its mouth. To retain working-class voters, it needs to demonstrate that at a minimum it strives for a society less ruthless and cruel to ordinary people than the Republican Party envisions. But it can’t stray too far without losing its wealthy constituency to the Republicans. As a result, the Democratic Party is enamored of capitalist-friendly half-measures — inadequate means-tested social entitlements like Pell Grants, market-based solutions like Obamacare — that make it appear to take working-class issues seriously without rocking the boat too much.

The point of Bernie Sanders’s candidacy is to rock the boat. Sanders isn’t satisfied with Pell Grants: he wants universal tuition-free public college and university. He’s not satisfied with Obamacare: he wants Medicare for All, a tax-funded health-care program that covers all medical expenses for all people. These ambitious proposals are explicitly antagonistic to the corporate world. Instead of trying to appease both sides of the class divide, they propose an ultimatum. We can either continue to let a small group of elites benefit from the gatekeeping of education and health care, or we can excise the profit motive from those sectors — costing profiteers a great deal of money and strategic advantage in the economy — and guarantee them as social rights for all.

This is why Sanders doesn’t solicit money from the rich, and why they won’t give it to him. He views the world in terms of class conflict; the rich and the rest are locked in struggle, and when one side wins, the other side loses. “If there is going to be class warfare in this country,” he says, “it’s about time the working class won that war.”

Taking donations from the rich is a silent promise to look after their interests when tough political choices need to be made. The rich know this; otherwise, they wouldn’t pay so handsomely. By refusing corporate money, Sanders wants to signal to them, and to working people, that he will not be solicitous of the billionaires’ interests when making policy decisions from the Oval Office. “You can’t change a corrupt system by taking its money,” says Sanders. His commitment is rooted in political principle and goes for the general election, not just the primary.

Sanders’s grassroots fundraising strategy has a second purpose, too. He wants to impress upon supporters that if he wins office, he will face immense pushback from capitalist interests, and will need all hands on deck. By rejecting money from the wealthy and instead focusing on engaging ordinary people in the political process, he’s getting supporters used to the idea that they will need to pool their resources and their efforts to build power that can compete with that of the capitalist class. As he frequently points out, a movement of millions will be necessary to support a Sanders administration in passing proposals like free college and Medicare for All against the wishes of the rich. This is the meaning of his slogan “Not Me, Us.”

By contrast, while Warren proposes to “take on giant corporations” and doesn’t mind ruffling feathers among sectors of the business elite, she stops short of alienating the liberal rich and the Democratic Party apparatus that caters to them. Her policy proposals imagine good corporations as key partners in social change, and she’s working hard behind the scenes to assure pro-corporate Democratic Party establishment figures they have nothing to fear. Giving the Democratic Party–aligned rich a middle finger while working to empower a mass working-class constituency that can fight on its own behalf isn’t really Warren’s theory of social change. It follows that her commitment to rejecting corporate money is squishier than Sanders’s.

Freezing out megadonors, however briefly, is a good thing. But we should see Warren’s temporary abstention from big-dollar Democratic Party fundraising practices for what it is: rather than deriving from deeply held principles, it’s primarily a strategic adjustment in a political climate created by Sanders. To wit, Warren’s big-money ban precisely coincides with the one period during which Sanders will be her direct political opponent. Her commitment didn’t come a day sooner, and according to her it won’t last a day longer.

No leader who’s serious about drastically improving life for the working-class majority can play for both teams. Every solid victory for the working class will come at least partly at the expense of the capitalist class. Bernie Sanders knows what team he’s on. All the others, even when they do things we like, are simply responding to the ultimatum he’s presented.