"Clearly the district wanted a lot of change", Mr Capuano told supporters on Tuesday as he conceded. "I'm sorry it didn't work out, but this is life". Since she will not face a Republican opponent in November's midterm election, Pressley will most likely become the first African-American woman to represent MA in the U.S. House of Representatives.
She'd argued on the campaign trail that systemic inequalities had worsened in a district that was once represented by John F. Kennedy and where the majority of voters are nonwhite.
Pressley enjoyed an endorsement from Ocasio-Cortez on Twitter.
Wu, a programer and video game designer who rose to prominent after she became the target of threats and online attacks for calling out misogyny in the gaming community, had called for single-payer healthcare, a guaranteed minimum income and other progressive initiatives.
"I have been really furious about the constant charges being lobbed against me about identity politics that, by the way, are only lobbed against women and candidates of color", she said in one debate.
Ayanna Pressley's reaction to her historic upset victory in a Democratic primary for a Massachusetts House seat quickly went viral on Tuesday.
Pressley's win was the latest in a streak of primary victories by younger, more diverse Democratic candidates against established rivals before the November 6 election.
Elsewhere in the state, Congressmen Joe Kennedy, 37, won a comfortable victory in his primary and fellow Democrat Richard Neal, 69, fended off a younger challenger.
Pressley has served on Boston's city council since 2009, with a mandate to support women and girls.
Pressley is a commanding stage presence who frequently ditches microphones; she doesn't need them. Just a third of the population is white, with black, Hispanic and Asians constituting most of the other two-thirds.
Secretary of State William Galvin, the longest-serving constitutional officer in state history, held off his strongest Democratic primary challenge in years from Boston City Councilor Josh Zakim.
She made a slogan of the line "those who are close to the pain should be close to the power". As FiveThirtyEight reports, a MA candidate has followed in the footsteps of the young Ocasio-Cortez with a surprising upset against a mainstream Democrat challenger on Tuesday evening.