Ayanna Pressley speaks at her congressional campaign kickoff in Cambridge. (Photo by Michael Jonas)

SHE EMERGED ON Monday as the leading voice of “the Squad,” not because hers is the loudest but because, in fact, it seems the most measured. Ayanna Pressley, diplomat of the bomb-throwers, seems like something of a contradiction in terms. But that’s how Boston’s freshman US representative is being pegged in the wake of the most high-profile moment of her young congressional career.

When the four minority freshman congresswomen convened a Capitol Hill press conference on Monday to respond to President Trump’s racist weekend tweets directed at them, it was Pressley who came to the mic first.

Fellow Squad member Rashida Tlaib told the Globe they chose Pressley to speak first because she sets a “positive, loving tone.”

“We wanted her to lead us in taking on the biggest bully probably in our lifetime,” said the Detroit congresswoman.

At age 45, Pressley is the senior member of the foursome, which also includes Rep. Alexandria Ocasio-Cortez of New York and Rep. Ilhan Omar of Minnesota.

The four freshman lawmakers have emerged as the brash shock troops of the new left-leaning activist wing in the Democratic Party. They drew the ire of Speaker Nancy Pelosi as the only four Democrats to vote against a recent measure to send more money to border detention facilities. Ocasio-Cortez inflamed the situation further by charging Pelosi with singling out “newly-elected women of color.”

For two them — Pressley and Ocasio-Cortez — their willingness to challenge the status quo was evident in their election itself, upending veteran Democratic incumbents in primary elections last year.

The other two members, meanwhile, have shown plenty of fight of their own, with Tlaib famously telling a rally of activists hours after her January swearing-in what she had in mind for the president. “We’re going to impeach the motherfucker,” she exclaimed.

While Pressley’s membership in the bomb-tossing quartet is serving as her introduction to a national audience, those who followed her career in Boston would probably characterize her quite differently — as the consummate inside player. She spent more than a decade as a congressional staffer, first for Rep. Joseph Kennedy II and then for Sen. John Kerry. During her decade on the Boston City Council, Pressley was never known for high-profile tangles with Mayor Tom Menino or, following his retirement, Mayor Marty Walsh.

“There are real distinctions between them,” Attorney General Maura Healey says of Pressley and her three congressional colleagues in an interview with Globe columnist Adrian Walker, pointing to Pressley’s long track record in politics.

“I don’t think she had the option to throw bombs in the same way until she was surrounded by other like-minded individuals,” UMass Boston political science professor Erin O’Brien told the Globe. But that seems to ignore the years when she served with outspoken progressive councilors such as Tito Jackson, Michelle Wu, and Andrea Campbell.

Former congressman Barney Frank said Pressley has stood out from the other three Squad members by not offering the same sort of charged rhetoric, making him wonder why she’s joined up with them in their challenge to party leaders.

“My puzzlement about Pressley is that I haven’t seen her do anything that seemed to me mistaken the way the other three have, but then she joins them, and apparently agrees with their approach, and I think their approach is very wrong,” Frank told the Globe.

Critics say that more measured approach is not what Pressley displayed at a Netroots Nation conference on Saturday. “We don’t need any more brown faces that don’t want to be brown voice. We don’t need any black faces that don’t want to be a black voice,” she told the crowd, comments that a Herald editorial slammed as a threat against anyone who would stray “from the progressive playbook.”

If Pressley’s split political personality as veteran inside player now pushing change sometimes seems hard to square, perhaps it also positions her as someone who can bridge the emerging intra-party divide and help Democrats avoid the sort of squad the party is more known for — the armed one that forms in a circle.

Michael Jonas works with Laura in overseeing CommonWealth Beacon coverage and editing the work of reporters. His own reporting has a particular focus on politics, education, and criminal justice reform.