In the battle over ideas in the Democratic party, it’s clear the moderates aren’t getting much quarter. This was on display at the “Ideas Conference” held Tuesday by the Center for American Progress, the central policy and personnel clearinghouse for Democratic administrations. Just before the event, the think tank released “A Marshall Plan for America”—an ambitious jobs guarantee via “a large-scale, permanent program of public employment and infrastructure investment.”

The racially and gender-diverse main speakers ranged from the liberal to the very liberal. Senator Elizabeth Warren gave a strong lunch keynote demanding strong antitrust enforcement to break up concentrated economic power. Senator Kirsten Gillibrand extolled the necessity of paid family leave, Senator Cory Booker demanded universal health care, Senator Kamala Harris called for the total decriminalization of marijuana and the election of “progressive prosecutors” nationwide, Representative Keith Ellison called Trump’s voter-fraud commission a scam and a “set-up,” and Senator Jeff Merkley demanded a green transformation of the energy economy that would put “every coal electricity-generating plant into a museum by the year 2050.”

Many of these speakers, particularly the ones gifted a “keynote” speaking slot, are widely rumored to be seeking the White House, and the mainstream media portrayed the event as a cattle call for 2020 candidates.

But there was an awkward absence: Senator Bernie Sanders. He was not invited to the “Ideas Conference,” and his exclusion makes clear that, while Democrats are converging around a general set of ideological principles, the party still faces some serious coalition-building problems.

CAP president Neera Tanden explained to The Washington Post that “We were trying to emphasize a new generation,” and a CAP spokesperson told The Nation that nobody who ran for president before was invited.

That’s true as far as it goes, but with any scrutiny it feels more like a post facto justification for not including Sanders. There’s a big difference between Hillary Clinton—now a private citizen with no future electoral plans—and Sanders, a sitting senator who polls as the most popular politician in the country and who has pointedly not ruled out a 2020 presidential campaign. The press materials for the conference proclaimed it would “bring together national leaders of the progressive cause,” and there’s no real way Sanders doesn’t fit that description, or rationally should have been excluded simply because he ran for president last year. (The presence of Susan Rice and Tom Daschle onstage also puts considerable strain on the idea that only new voices were being elevated.)

Attendance was restricted in other ways, too. There was no website for the event, which was held at the swanky Four Seasons hotel, nor a way for anyone to attend unless CAP sent a personal invite. (Though one could pay $1,000 to attend the “Progressive Party” after the conference.) The audience was primarily donors to the think tank, as well as CAP’s professional allies across DC and representatives of some grassroots organizing groups, including Wall of Us, Town Hall Project, Action Group Network, Men for Choice, New Leaders Council, Action Alliance, Rise Stronger, Run for Something, 5Calls.org, Democracy Labs, and Flippable.*

But an invite-only event at one of the most expensive hotels still created a distinctly elite feel, despite the genuinely populist economic agenda that was being promoted.* And that’s the real split in the party right now: between the grassroots and the establishment represented at the Four Seasons on Tuesday. It’s less about Bernie versus the Clintonistas, but rather that the wide array of socialist activists, community organizers and radical labor groups that existed for quite a while in Democratic Party politics and lined up behind Sanders when he ran for president are now feeling energized and emboldened.

That movement exists on an entirely parallel track to the professional left in DC. A lot of those groups will be meeting in Chicago in early June for their own version of an ideas conference. Sanders will address “The People’s Summit,” which is being held by the National Nurses United, Progressive Democrats of America, Democratic Socialists of America, the Food & Water Action Fund, Our Revolution, and others.

“CAP couldn’t have made [the Ideas Conference] feel any less like that if they tried,” joked one progressive activist who attended Tuesday but wished to remain anonymous for professional reasons.

It’s hard to envision a functional political party where there’s such a fissure between the elites and the grassroots. It has already caused the Democrats no shortage of pain, even in the Trump era: The race for DNC chair was also much less about ideology and more about who would get control of the party mechanics—the established hands or the newcomers.

Elbowing Sanders out of the party isn’t going to solve this problem, though many Democrats seem intent on doing it. Politico ran a story on the same day as the Ideas Conference quoting several top Democrats who clearly want Sanders to go away, while blaming him for the party rifts. “He’s a constant reminder. He allows the healing that needs to take place to not take place,” one said.

Meanwhile, being shunned by party bosses is rocket fuel for the Sanders movement. “If you want to understand why establishment Democrats lose, look at CAP. They hold their…grassroots conference at the Four Seasons and don’t invite grassroots progressives,” one progressive strategist affiliated with Sanders but not authorized to speak for him told The Nation. “They charge $1,000 per ticket to attend their ‘Progressive Party’…and eat canapes while wondering why they are out of touch with the rest of the country.”

*A prior version of this article quoted Markos Moulitsas referencing “that grassroots Bernie thing.” Other news outlets reported this quote as well, but it appears Moulitsas said “grassroots burning thing.” We have removed the reference and regret the error.