WASHINGTON -- On April 6, a host of Democrats will gather in a magisterial Georgetown rowhouse to celebrate Hillary Clinton. For an entrance fee of $500 ($250 for "young professionals" under age 35), donors will have the chance to rub elbows with Sen. Sherrod Brown (D-Ohio) former Sen. Carl Levin (D-Mich.) and Gary Gensler, the toughest bank regulator of the Obama era. These liberal icons -- their names are listed in bold blue type on the invitation -- are the event's main attractions. Clinton herself will not attend.

Levin, of course is an old party hand, while Brown endorsed Clinton months ago and Gensler serves as her campaign's chief financial officer. It isn't terribly surprising to see such figures supporting their party's presumptive nominee.

But the event's supporting cast -- a cadre of serious Democratic nerds given second-tier billing in smaller print -- is more significant. The event was organized by Andy Green, a former lawyer for Securities and Exchange Commissioner Kara Stein. Before joining the SEC, Green was a top staffer for Sen. Jeff Merkley (D-Ore.). He and former Levin aide Tyler Gellasch are responsible for ensuring that the Volcker Rule -- the toughest financial reform in the Dodd-Frank Wall Street overhaul -- became law. Gellasch will be joining his old friend at the event, as will Raj Date, one of Elizabeth Warren's first hires at the Consumer Financial Protection Bureau. Elise Bean, the Democratic Party's foremost expert on offshore tax haven abuse, is attending, as are a handful of other liberal technocrats who built their careers on corporate accountability -- the kind of people Warren and Sen. Bernie Sanders (I-Vt.) would like to see in any Democratic administration.

This is, of course, a sign that the progressive wing of the party elevated by Warren's career in Washington is coming around on a Clinton nomination. But there's a subtly sinister bend to the wonkfest: It's being hosted by Julie Chon, a former Dodd staffer who cashed out to help a major hedge fund siphon money from the federal government.

Chon now works for Perry Capital, a $10 billion hedge fund run by Clinton megadonor Richard Perry. One of Perry's major projects is an effort to exploit technical details of the federal government's 2008 takeover of mortgage giants Fannie Mae and Freddie Mac. Right now, profits from Fannie and Freddie go to the U.S. Treasury. Perry argues they should flow to him.

Perry brought Chon into the fold in 2012 to try and talk policymakers in Washington into making the switch, according to Bloomberg. He is now suing the federal government for failing to comply, with a case based largely on a 2008 law that Chon helped write.

Every fundraiser is an attempt to purchase influence with a candidate. Republicans and corporate Democrats do it all the time, and it's hard to fault policy nerds for trying to stay relevant. But if influential progressives were confident about breaking into Clinton's world, they wouldn't have to line up at the home of a revolving-door hedge funder to make their pitch. As the primary season winds down, the Elizabeth Warren wing of the Democratic Party has met its first make-or-break moment.

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Warren, of course, didn't run for president. She already has a Senate perch that allows her to broadcast the virtues of her economic agenda. The few months of amplification she would receive from a presidential campaign, Warren reasoned, wouldn't be worth the price of losing to Clinton. A loss would crystallize the corporate wing of the Democratic Party's hold on its future and demonstrate that Democrats really aren't all that passionate about the issues that, after all, didn't carry the day. With the entire party establishment lined up behind Clinton, the deck was clearly stacked against a Clinton challenger. Superdelegates would have forced Warren to win at least 60 percent of the delegates decided by mere voters in order to clinch the nomination.

Warren is probably re-evaluating that analysis after Sanders' surprising strength, but in the summer of 2015, the more plausible benefits of a primary challenge seemed to be those of a losing campaign -- holding a more conservative candidate's feet to the fire, and forcing them to acknowledge the party base.

Warren didn't believe those benefits would last. Forcing candidates to swerve leftward during a primary only matters if they stay there once in office. But Democrats who survive a liberal challenge almost never maintain their progressive postures once they win office. Typically, they flee to more conservative territory as soon as the general election campaign begins.

When Warren declined to step up, Sanders filled the void. And he has been a far more effective spokesman for Warren's issues -- breaking up the banks, rethinking corporate-friendly trade, raising the minimum wage -- than even his most ardent supporters had expected. But as he fades in the polls, Warren's early fears may be coming to fruition.

Barring an act of God, Clinton will be the party's standard-bearer in November. Economic populists may have inflicted enough pain on Clinton over the past several months to force her to take their concerns seriously in office. But there's a very real danger that Clinton is simply showing the world she doesn't need them. Sanders is crushing her with small donors. She's winning anyway. She has attacked single-payer health insurance and assailed tuition-free college. She's winning anyway. She has belittled the very basis for campaign finance reform in order to defend her paid speeches to Goldman Sachs. She's winning anyway. At Saturday's debate, she twisted her vote for the bank bailout into a dishonest attack on Sanders' commitment to manufacturing workers. And she's winning anyway.

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Warren could not have foreseen the damage that Donald Trump would do to her plans. Democrats have been watching the billionaire's political ascent with a mixture of horror, fascination and elation. It's frightening to see a fascist demagogue take over an American political party. It is also a joy to watch the Republican elite melt down as the racist alliance that has fueled their party's electoral relevance for almost a half-century makes its apotheosis.

Long-term, Trump's campaign is demographic suicide for Republicans. But the basic physics of a two-party system require that when one party blows up, both parties must change. While Trump is a more dangerous general election matchup for Clinton than most Democrats recognize, he is a gift to elite Democratic insiders seeking to wrest power from Warren's acolytes. Trump's effect on the Republican Party is obvious: He's broadening the bounds of acceptable debate. Marco Rubio -- a tea party favorite of the ultraconservative Heritage Foundation -- is now beloved by the Republican establishment. Mitt Romney -- an aristocrat who made self-deportation the immigration platform for his 2012 campaign -- is now performing public acts of outrage over Trump's naked racism. What was previously expressed in coded language and winks and nods is now the open celebration of execution by pig's blood.

The same phenomenon is shifting the policy priorities of the Democratic Party in a different way. What is any sane progressive going to do when there's a fascist on the other ticket? Clinton doesn't need to convince people that she cares about corporate accountability or economic inequality when Trump is out there saying the Bush torture program wasn't cruel enough. The Clintons have been warning liberals that it's either them or the brownshirts for decades. Now the brownshirts have finally arrived.

Sanders supporters are telling themselves a story about how his candidacy compelled Clinton and the party establishment to confront the progressive base. They're at least half right. The Sanders campaign did force the party to grapple with progressives. The question is whether progressives are going to survive the struggle.

A few of them will find out on April 6, at a $1.8 million home in Georgetown.

Clarification: This article has been updated to clarify that Green is no longer employed at the SEC.

Zach Carter is a co-host of the HuffPost Politics podcast "So, That Happened." Subscribe here or listen to the latest episode below: