CAMBRIDGE, Mass. — Blink and you might miss her.

The woman who could be the next progressive superstar was standing by a small folding table outside a busy T stop in Central Square as commuters streamed by one evening last week.

In a deep blue congressional district once represented by John F. Kennedy and legendary House Speaker Tip O'Neill, Ayanna Pressley is trying to topple a 22-year incumbent in the next big test for insurgent Democrats.

"I knew that I would be out-endorsed, I knew that I would be out-fundraised and out-spent, and now the challenge is on me to out-organize," said Pressley, who in 2009 became the first woman of color elected to Boston's City Council, 379 years after its founding. "This is a fight for the soul of our party."

Those who did stop seemed engaged. Black women came to hug her and say how inspiring it was to see someone who looks like them in power. Millennials pulled out their earbuds to pose for selfies. And MJ Jensen, with grey hair and plastic-rimmed glasses, joked that while some of her best sons are men, "It's time to let us screw stuff up for a change."

Women have been winning Democratic primaries at astounding rates this year, while insurgents have had a worse record. Pressley, a rising star before this race, may represent the last best chance to repeat the success of Alexandria Ocasio-Cortez, the progressive phenom who ousted a powerful Democratic congressman in New York City.

Pressley calls Ocasio-Cortez "my fellow sister in change," and Ocasio-Cortez likes to quote Pressley's line that "the people closest to the pain should be closest to power." On the night she won her primary, Ocasio-Cortez encouraged followers to vote for Presslsey.

But Pressley, a former Hillary Clinton surrogate whose political talent has been recognized by national Democrats for years, is not Ocasio-Cortez. And Rep. Mike Capuano, D-Mass., who has an impeccable progressive record and took the primary threat seriously from the beginning, is not Rep. Joe Crowley D-N.Y.

Rather than ideology, the Sept. 4 primary may be more a test of Democrats' desire for fresh leadership, and especially from women and people of color, in one of the few majority-minority districts in the country represented by a white man.