They spent their first nine months in office hiding from the limelight, turning away from the TV cameras and urging caution about the scandals enveloping President Trump.

Then, in just a few days, after texting and holding conference calls, several dozen freshman Democrats stepped out from the protective shield of House Speaker Nancy Pelosi (D-Calif.). They were ready, particularly those with national security backgrounds, to push to impeach the president whose election had propelled so many of them to run for office last year.

“It’s interesting. We’re all trained to make hard decisions in tough climates,” said Rep. Mikie Sherrill (D-N.J.), a Navy helicopter pilot and Russian policy expert who served as a federal prosecutor before winning a longtime GOP seat in 2018. “This was actually not that hard a decision. This was such a clear violation of our norms, such a clear violation of our national security.”

On Monday night, Sherrill and six other freshmen with credentials in the military, defense or U.S. intelligence published an op-ed in The Washington Post calling for an impeachment inquiry after Trump acknowledged that he pressed Ukrainian leaders to investigate former vice president Joe Biden, a leading Democratic rival for the 2020 election.

That proved seismic, helping move other wavering Democrats from swing districts off the fence.

“I was very much affected by my fellow members who are all national security types, former military, former CIA. And their deep concern, their very deep concern, over these allegations when they have consistently been rebuffing the idea of impeachment,” said Rep. Susan Wild (D-Pa.), who flipped a seat Republicans had easily held for 20 years.

This national security group, after months of bristling at the attention given to the liberal “Squad” of four freshmen from reliably Democratic strongholds, took the step that proved most significant in pushing Pelosi. Once they were on board, Pelosi had no one left to protect.

Exiting the Democratic caucus meeting Tuesday afternoon, Sherrill did an impromptu live interview with CNN and other outlets. Then, around a corner in the basement hallway, she expounded on her reasoning for supporting the impeachment process.

Upstairs, two of her best friends, Reps. Elissa Slotkin (D-Mich.) and Abigail Spanberger (D-Va.), stood side by side in the Capitol’s Statuary Hall prepping for separate TV interviews. A former Defense Department official and CIA analyst, respectively, Slotkin and Spanberger have also shied away from national attention, part of a group of 31 Democrats holding districts that Trump won in the 2016 elections.

With Republicans needing just 19 more seats to reclaim the majority, Pelosi catered to these swing-seat Democrats, believing impeachment certain to end in a party-line vote and acquittal in a Senate trial would probably hurt these freshmen in 2020.

Throughout the first phase of the Trump investigations, focusing on Russian interference in 2016, these Democrats found that their constituents were confused by the complicated and long-running investigation by special counsel Robert S. Mueller III. Instead, while other freshmen got media attention for bashing Trump, this group focused on kitchen-table issues like health-care costs and infrastructure projects.

So as the calls for impeachment soared, well past a majority of the caucus during the late-summer recess, these Democrats stayed quiet. Liberal activists tried to jam their town halls, but most Democratic aides reported that aside from one or two impeachment questions, the overwhelming majority of concerns focused on local economic matters.

Even after the Ukraine story broke, some said there was no uptick from anti-Trump activists. Rep. Dean Phillips (D-Minn.), who won a Twin Cities suburban seat over a GOP incumbent who had never won by fewer than eight percentage points, said the new push came from “a lot of independents and a lot of Republicans” alarmed by the Ukraine matter.

“I’ve heard from many more that had been agnostic perhaps before, but recognize that this is an entirely different circumstance,” he said.

“Yes, with this issue, people understand it better than they did the Mueller report,” said Rep. Donna Shalala (D-Fla.), who previously opposed impeachment because of her experience in the Clinton administration Cabinet during the 1998 impeachment.

Sherrill said she simply had no idea what the politics were: “This is so new. I’m not sure how the voters will receive this.”

To be sure, a dozen or so swing-seat Democrats remain mum, declining so far to take a position even after Pelosi made clear that she would press ahead and that a full House vote on some articles of impeachment seems likely in the coming months.

But no one spoke out against impeachment in their Tuesday afternoon huddle in the Capitol basement.

“The caucus is going to stick together, the speaker speaks for us now,” Shalala said. “And my district will understand why we have to stand up now.”

In many ways, the decision came down to how they would define themselves as a class that came to Washington believing they could change the place, rather than let this town change them.

The classic congressional move would have been to stay quiet, avoid taking a position on such a controversial decision as impeachment, and just hope the storm blew over by the time elections rolled around next year.

But the more they talked, the more they realized that they did not want to win reelection by running from the big decisions.

Do you really want to be here, one adviser asked his boss, a first-time politician, if that’s what you have to do to win reelection? The answer was no.

And for the national security squad, the issue was even more personal to defining who they were on Capitol Hill. What little attention they sought this year, they wanted the focus to be on national security.

And here was Trump, in a span of a few days, denying foreign aid to an ally in the fight to contain Russia, while demanding Ukraine’s new president investigate 2020 rival Biden. Trump has denied using the money as leverage.

After so much time in the background, they decided it was time to come into the spotlight.

“These are clear violations, a clear attempt to influence our 2020 elections, and so I felt very strongly that I had to come forward,” Sherrill said.