Rep. Michael Capuano concedes defeat to Boston City Councilor Ayanna Pressley in the 7th Congressional House Democratic primary, Tuesday, Sept. 4, 2018, at his primary night party in Somerville, Mass. (AP Photo/Elise Amendola)
Rep. Michael Capuano concedes defeat to Boston City Councilor Ayanna Pressley in the 7th Congressional House Democratic primary, Tuesday, Sept. 4, 2018, at his primary night party in Somerville, Mass. (AP Photo/Elise Amendola) Credit: Elise Amendola

In a political stunner, incumbent Democratic U.S. Rep. Michael Capuano lost Tuesday’s primary to Ayanna Pressley, a Boston city councilor who is virtually assured of becoming the first black woman to serve Massachusetts in Congress.

The 44-year-old’s upset over a 10-term incumbent congressman underscores the shift underway in a Democratic Party whose base is seeking younger, more diverse candidates who embrace progressive policies. Her victory comes just two months after Alexandria Ocasio-Cortez similarly defeated a top House leader in a primary for a New York congressional seat.

Ocasio-Cortez tweeted a selfie of both women together and wrote, “In June, I won my primary. Tonight, she won hers. Here’s to November.”

Pressley, the first black woman to serve on the council, is now on track to represent an area of Massachusetts once served by Democratic icons Tip O’Neill and John F. Kennedy.

“Change is coming and the future belongs to all of us,” Pressley told wildly cheering supporters Tuesday night.

A subdued Capuano told supporters he did everything he could to win re-election.

“Apparently the district just is very upset with lots of things that are going on. I don’t blame them. I’m just as upset as they are, but so be it. This is the way life goes,” he said.

The race between Capuano and Pressley was perhaps the most closely watched contest in Massachusetts, especially since Pressley drew comparisons to Ocasio-Cortez.

The 7th Congressional District is the only one in the state where minorities comprise a majority of the population.

“This is a fight for the soul of our party and the future of our democracy,” Pressley said Tuesday while campaigning in the district. “And a reliable vote is not good enough.”