As the Democratic primary heats up, the gloves are coming off. It was both predictable and predicted that the same party eminences who hectored Democrats about civility and not “eating their own” would strike the first blow.

When Bernie Sanders’s tax returns revealed that income from the sale of his books had made him a millionaire, ThinkProgress, the website financed by and run out of the Center of American Progress and its Action Fund called it “very off brand and embarrassing,” and followed with a snarky video suggesting—inaccurately—that Sanders had stopped denouncing millionaires as he moved closer to becoming one.

In a letter to the CAP Board, Sanders chastised CAP for “using its resources to smear” him and other candidates embracing progressive reforms and called for an end to this “counterproductive negative campaigning.” Neera Tanden, the head of the think tank and a sharp-elbowed tweeting ally of Hillary Clinton, backtracked immediately, disclaiming editorial responsibility for the website and later admitting that the video was “overly harsh and does not reflect our approach to a constructive debate of the issues.”

This Beltway brouhaha is a small-bore political spat that most voters will ignore. But it does expose deeper realities that will play out over the next several months. “Politics,” as Peter Finley Dunne quipped, “ain’t bean bag.” While Democratic presidential candidates have all expressed a desire to avoid personal spit-ball fights, their operatives and zealous supporters will have at it. Every candidate will be vetted—on character, on record, on where they get their money, as well as on issues. The CAP-Sanders exchange is mild compared to what is coming.

The stakes are very large. Democrats are universally committed to evicting Donald Trump from the White House. At the same, however, they are in the midst of an historic debate about the party’s agenda, coalition, political strategy, and future. The party’s establishment is under siege. Its neoliberal policies have failed to work for most Americans. By 2016, its political strategy had cost the party control of the House, Senate, nearly a thousand state legislative seats, and, unimaginably, loss of the presidency to the most unpopular political candidate in the history of opinion polls.

Inspired by the Sanders insurgency in 2016, progressives now are driving the issues debate, and—aided by the provocations of the Orange Menace—fueling the party’s political resurgence. Now, in the presidential primaries, Bernie Sanders and Elizabeth Warren among others are mounting campaigns that directly challenge the policy agenda and the political strategy of the establishment.

It’s emblematic that CAP is entangled in this first spat. CAP, by far the best-funded think tank in the Democratic constellation, is, as described by The New York Times, “a legacy Clinton institution,” founded by John Podesta, Bill Clinton’s former chief of staff and Hillary’s campaign chair, and now led by Tanden, a close Clinton confidant. CAP is a big tent, with many talented progressives working there, but the center ring has always been center-liberal—socially liberal while reflecting more centrist perspectives on economics and foreign policy. What Neera Tanden scorns as “crazy, radical ideas”—Medicare for All, Tuition Free College, a $15-per-hour minimum wage, a Jobs Guarantee, the revolt against corporate trade deals, and more—have come at CAP, not from it. Its slap at Sanders reflects an establishment that feels threatened.

Money is central to the dispute. It is risible and revealing that ThinkProgress chose to scorn Sanders for his indictment of “millionaires and billionaires.” As Paul Krugman notes, nothing more embitters the party elite than the Sanders and Warren critique that big money corrupts and compromises the party. Politics-as-usual is a billion-dollar operation. Deep pockets and entrenched interests have inordinate influence. The Democrats’ big donors tend to be enlightened on social issues, but often neoliberal on economics. They are down with women’s right to choose or gay rights, but unsettled at best at talk about extreme inequality, or challenges to the corporate trade regime.

The party establishment—and the big money that pays for the party—isn’t about to cede control. The party’s elite mobilized to block Keith Ellison, then co-chair of the Congressional Progressive Caucus and a prominent Sanders supporter in the primaries, from becoming chair of the DNC. The new head of the Democratic Congressional Campaign Committee, Cheri Bustos, has announced that the DCCC will cut off any campaign consultant who works with a challenger to a sitting Democrat, while filling the DCCC coffers with contributions from the rich and corporations.

Not surprisingly, when Bernie Sanders emerged as an early front-runner in the polls (which measure little more than name recognition at this stage), raising the most money from the largest base of small contributors, and brandishing his own independent communications capacity, the establishment grew alarmed. The New York Times reports that “[f]rom canapé-filled fund-raisers on the coasts to the cloakrooms of Washington,” centrist Democrats have begun meeting about “what to do about Bernie.” David Brock, one of those prating about civility only a few weeks ago, now is trolling for funds for an anti-Sanders campaign that, he says, should begin “sooner rather than later.”

The party establishment wants it both ways. It wants and needs the growing energy of the progressive activists and can’t afford to alienate them. It also wants control and is terrified that Sanders might actually win the nomination. A Sanders candidacy, many believe, would scare off votes from the suburban middle class that Trump has alienated, turn off big-money donors, and lead Democrats to a catastrophic loss, like Goldwater in 1964. This mirrors the hysteria of the Republican establishment faced with Donald Trump’s much more scabrous candidacy in 2016. In both parties, the establishment is too disorganized to unite behind one candidate. In 2016, the traditional Republican money went mostly to the safest choice, Jeb Bush, whom Trump eviscerated. If much of the Democratic establishment decides to throw in with the safest face, Joe Biden, they are likely to suffer a similar outcome.

Trump will help mobilize and unify Democrats, no matter how fierce the primary battle. One theme of the Sanders opponents is that he is a divider who will split the party if he loses. Liberal columnist Paul Waldman, who usually is more sensible, suggests Sanders was only “too excited to get in a kerfuffle” with CAP, because he’s “an outsider, an insurgent,” for whom “no set of [Democratic Party] policy positions” will ever been enough.” If Sanders loses the nomination, the “bitterness of 2016” is likely to repeat itself in 2020, Waldman speculates, with Sanders voters “harder to bring into the fold that those of other losing candidates.”

Sanders is, of course, an insurgent, but the rest of this is pure invention. In fact, Sanders worked to frame the party platform in 2016, praised it as the most progressive platform in history, and stumped across the country for Clinton on that basis. Although many Sanders activists were bitter about the DNC thumb on the scale in 2016, a smaller percentage abandoned Clinton than the percentage of Clinton primary voters who abandoned Obama in 2008 after that bitter primary. Sanders has already declared repeatedly that the most important task is to get rid of Donald Trump and has stated unequivocally that he will support the nominee.

Division is more likely to threaten not if Sanders loses but if he wins. When Trump won, the Republican establishment split many ways, supporting alternative candidates, announcing refusal to vote for Trump, cutting off donations. Will the money wing of the Democratic party and its retainers unite behind a Sanders candidacy to get rid of Trump, or will the shocking loss of control be unacceptable? A liberal billionaire—the feckless Howard Schultz—is already toying with a third-party candidacy because, he claims, Democrats have gone too far left. Sanders, Warren, and the movement left of the party are on the rise and will stay and build. The real question is whether a threatened party establishment will stay unified to get rid of Trump or split rather than support an insurgent’s victory.