Two days after the town hall, on Sept. 18, news broke that a government whistle-blower had reported to the inspector general of the intelligence community that he had concerns about a troubling conversation Trump had with a foreign leader. A few days later, with details still scant, Spanberger started thinking about whether this, finally, constituted clear grounds for an impeachment inquiry. Her campaign manager, Bettina Weiss, was driving her to a pig-roast fund-raiser for Senator Mark Warner, driving past wheat fields and granaries, much of them owned by Republican voters, as Spanberger tried to figure out how strongly she felt about this breaking news. “How bad would it have to have been for him to come forward?” she said, wondering out loud about what the whistle-blower must have heard. Weiss turned the question on Spanberger: What would it have taken for you, as a C.I.A. officer, to sound an alarm? Spanberger opened her iPad, which had a keyboard attached, and started writing down her thoughts.

All weekend, Spanberger and her close colleagues were texting one another about the evolving news and what it meant regarding impeachment: Spanberger on the way back from the pig roast, Slotkin going home from judging a student hackathon, Houlahan sitting on a sunny spot on the floor in her bedroom. The sentiment among all of them was the same: This felt different. More clear. Higher stakes. At some point, Houlahan called up and circulated a document that Jason Crow of Colorado, a close colleague, drafted back in July. It called for impeachment over, among other things, Trump and his administration’s refusal to cooperate with congressional subpoenas, and Spanberger and the other women with military and service backgrounds had declined to sign on to it. “I’ve got my own thoughts,” Spanberger told her. “I’m going to send you something.” She sent around the writing she worked on in the car with Weiss and then started incorporating her colleagues’ thoughts into the document.

When Houlahan discussed with her chief of staff, Michelle Dorothy, that they were all considering backing the impeachment inquiry, Dorothy was blunt with her. “I think people will see this as a highly partisan thing,” Dorothy told her. “And so this makes it harder for you in your district.” Houlahan told Dorothy that if she were going to lose her seat over that decision, she was O.K. with that. Dorothy said, In that case, O.K.

Spanberger, Houlahan and Crow spent a chunk of the day on Monday in Houlahan’s office staring up at the words on a large screen, polishing the prose with colleagues remotely, drafting an op-ed that they planned to publish as soon as possible. Their statement laid out the accusations clearly. “If these allegations are true,” they wrote, “we believe these actions represent an impeachable offense.” At 5 p.m., they let the speaker know the piece would be running that evening in The Washington Post. The national-security angle was a good one, Pelosi agreed; the party would run with it.

If it was not perfect statesmanship — some leadership staff members thought their point of view might sway more voters if it were published in a less liberal venue — at least the timing was ideal: If they were going to come out on the side of impeachment, better that they do so before Pelosi announced her desire to pursue an impeachment investigation, lest they look as if they were simply following orders from the liberal elite. Their op-ed prompted Politico to declare: “The dam begins to break on impeachment.”

The last week of September, Pressley spoke at the 50th-anniversary gala of Naral, an abortion rights group, at the Capitol Hilton honoring Hillary Clinton and Representative Barbara Lee of California, an event that drew close to 500, including at least a dozen House members. Pressley had been asked to introduce Lee, a longtime mentor, at the event, and she seemed relaxed and happy as she ran into people in the hallway of the hotel. She gave the wife of a congressman she knew well a big hug; she embraced a woman who approached her to say she had supported her since her first bid for City Council. She ran into Spanberger, who introduced her to a woman who designed scarves popular among the first-year congresswomen, as they feature sketches of all of their faces. “Thank you for your activism through artistry!” she said. When Pressley went to the lectern to introduce Lee, she started out talking about how she herself had once been a hotel worker in a venue just like this one. “I know what it is for people to look over you and through you,” she said. “If you would do me the honor of thanking this evening’s wait staff.” The crowd rose to its feet and applauded.

The granddaughter of a Baptist preacher, Pressley spoke with confidence, poise and a compelling cadence. She looked like someone who had put the trials of the summer squarely behind her. During the six-week summer recess, she spent more time with her family than her schedule usually allowed; time out of Washington was a relief. She had needed it, she said, “both to adjust to the new normal and to put it in perspective.”