In the biggest surprise of 2018 so far, House Democratic Caucus Chair Joe Crowley (NY-14) lost his primary to 28-year-old former Bernie Sanders organizer Alexandria Ocasio-Cortez, 58 percent to 42 percent. Ocasio-Cortez, a Democratic Socialist who favors abolishing ICE, is now a lock to represent the Queens and Bronx seat. But more broadly, Crowley's loss reshuffles the next generation of House Democratic leadership.

The defeat is shocking because the 20-year incumbent runs the Queens Democratic Party and raised $3.4 million (to Ocasio-Cortez's $312,000), much of it owing from donors viewing Crowley as an imminent candidate for Speaker. But since his initial race 1998, Crowley had never been seriously challenged. Meanwhile, the 14th CD underwent a demographic shift: it's now 48 percent Latino and just 24 percent white.

Ocasio-Cortez's insurgency from the left had impeccable timing: her grassroots push got her coverage in outlets like Splinter News and The Nation and allowed her to build appeal with a tiny, very liberal primary electorate (barely five percent of the 14th CD's eligible voters cast ballots). But it was late enough to avoid setting off alarm bells among groups who might have rallied to aid Crowley, who once headed the centrist New Democrat Coalition.

Besides differences in ethnicity and ideology, gender and age undoubtedly played roles. In a year when Democratic primary voters are desperate for change, Ocasio-Cortez is half Crowley's age. And, her victory continues a string of breathtaking success for women in Democratic primaries. Those contrasts might have made it harder for Crowley, as opposed to other New York Democrats who survived, to go on the attack.

Because the primary featured so many unique contrasts, don't expect the upset to set off a tsunami of Bernie-crats toppling House Democrats. After all, we're already more than halfway through the primaries and Crowley is the first who's lost. But one Democrat whose allies will be on higher alert is Rep. Mike Capuano (MA-07), who faces a September primary against much younger Boston Councilor Ayanna Pressley in a majority non-white seat.

The Tea Party waves of 2010 and 2014 didn't topple many House GOP incumbents in primaries, but they did take out House Majority Leader Eric Cantor. Much in the same way, the hardcore Resistance took out Crowley but could help power Democrats to gains this fall.

It's no secret that Crowley had been angling for the Speaker's gavel in the event Democrats took back the House but Minority Leader Nancy Pelosi couldn't wrangle 218 commitments. However, the case for Crowley was already shaky. If Democrats took back the House by the margin of their female victors, could they have justified tossing the first female House Speaker and embracing two white New York men as their House and Senate leaders?

Crowley's exit begins the conversation about the next generation of House Democratic leadership anew. Less senior members likely to receive more attention include Reps. Cheri Bustos (IL-17), Joe Kennedy III (MA-04), Linda Sanchez (CA-38), Katherine Clark (MA-05), Seth Moulton (MA-06), Ruben Gallego (AZ-07) and others. And, any aspirants will need to be on good terms with the party's increasingly dominant progressive base.