Capuano was the only Democratic incumbent in MA to lose a primary Tuesday night, with three others easily fending off challenges from the left.
In 2009 she became the first black woman elected to the Boston City Council.
Her campaign slogan - "Change Can't Wait" - connected the Democratic optimism of the early Barack Obama years to the urgency of Donald Trump's presidency.
"It seems like change is on the way", Pressley told her supporters to rousing applause Tuesday night. Parallels between Pressley and Ocasio-Cortez were quickly observed as Pressley went up against a Democratic incumbent who was first elected into office in 1998.
Trump has angered Democrats with his comments describing some immigrants as criminals, his verbal attacks on black athletes protesting racism and a vow to overturn the Roe v. Wade decision that legalized abortion across the United States. Bernie Sanders (D-Vt.), she later supported it. Capuano also backed Sanders' quixotic health care scheme, which would cost approximately $32.6 trillion, according to Mercatus scholar Charles Blahous. John Kerry and an intern for former Sen.
"This is life and this is OK".More news: Amazon joins $1 trillion club, on pace to overtake Apple
More news: 'Defeat will stay with me forever,' says devastated Thiem
More news: Chaos mars hearing for Trump Supreme Court pick
Capuano is the second Democrat and fourth House incumbent to lose a primary for the November midterms.
Facing an uncontested general election for the district in November, Pressley, 44, is set to become the first woman of color to serve MA in Congress. Capuano, 66, is the second House Democrat to lose a primary to a progressive challenger this year, NY reports. From Andrew Gillum in Florida to Beto O'Rourke in Texas, the results suggest a shift towards a bolder, progressive agenda in stark contrast - and a reaction to - the managerialism of Hillary Clinton's last campaign.
The news that Ayanna Pressley defeated one of America's long-serving Congress members is a win not only for African-Americans but for women of colour. She ran on a platform of abolishing ICE-that's the Immigration and Customs Enforcement agency-and speaking for prisoners behind bars.
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.
Pressley, who labeled President Trump racist and misogynistic, said she knew when she launched her campaign that she "would find no favor with the Democratic establishment both here at home and in Washington".