Crowley, a 10-term incumbent representing New York's diverse 14th district and Number Four Democrat in the House of Representatives, had been considered a possible successor to Nancy Pelosi as party leader and even speaker, should Democrats reclaim the majority in November's midterm elections.
Instead the 56-year-old Crowley, chairman of the Democratic caucus, suffered the biggest shock upset to date in the 2018 political season, losing his primary to Alexandria Ocasio-Cortez, a Bronx-born Latina activist and Bernie Sanders supporter who has never held elected office.
According to a detailed profile this week in Vogue, just months ago Ocasio-Cortez was still working as a server in a restaurant. She identifies as a Democratic socialist.
Her impressive 15 percentage point victory could spell a leftward shift for the party that is squaring up against President Donald Trump's Republicans in the fall.
The campaign's Facebook page of Ocasio-Cortez highlights her political positions - expanded Medicare for all and tuition-free college - that are similar to those put forward by Sanders, a Vermont socialist who ran for the Democratic presidential nomination against Hillary Clinton in 2016.