WASHINGTON — The impeachment chorus in the House is growing larger and louder — and it's no longer just the safe-district partisan liberals who think it's time for the Judiciary Committee to open a formal inquiry into President Donald Trump's possible obstruction of justice.

The usual suspects from the progressive wing of the party have been more forceful behind closed doors and in front of TV cameras in recent days, and they've been bolstered by a discernible shift among less-prominent members of the rank and file.

"I’ve come to think that it is warranted at this point given what appears to be across-the-board defiance of congressional oversight and the rule of law by the administration," said freshman Democrat Tom Malinowski, who represents a highly competitive New Jersey district, in an interview.

"The law can survive the efforts of bad people to defy it," he said. "The law cannot survive the hesitation of good people to defend it."

The failure of former White House Counsel Don McGahn to appear before the committee to testify under subpoena Tuesday — after the White House instructed him not to show up — added force to the impeachment push.

But the dam isn't breaking on House Speaker Nancy Pelosi, D-Calif. — yet.

All along, her goal has been to keep her caucus together, and, at least for now, that still means not rushing into an impeachment process that many in her caucus believe could both fall short of ousting Trump and turn into a political bloodbath for Democrats at the polls next November.

Because the most politically vulnerable Democrats are in the toughest spot, caught between activists who want impeachment, and swing voters who are unenthusiastic about it or outright opposed to it, they are often the lawmakers least likely to take a strong stand one way or the other.

At the same time, the growing bloc in her caucus is the one that views the president's refusal to comply with subpoenas as a dangerous abuse of his power. With frustration building among them, Pelosi can't afford to stand pat, either.

"I think you’re seeing, as the administration continues to shirk constitutional responsibilities and make it impossible for Congress to execute its constitutional responsibilities, the remedy there is supposed to be impeachment," said Rep. Joe Kennedy, D-Mass. "So you’re seeing more and more people say, 'Hey, at a certain point what other avenues do we have?' The speaker’s indicated that there’s some additional strategies she wants to explore in our caucus."

Kennedy declined to say whether he favors beginning an impeachment inquiry now.

Like several other Democrats who spoke to NBC Tuesday, he appears to be giving Pelosi the latitude she seeks to find an alternative to a formal inquiry.

The cleanest way to start that process would be with a House floor vote, which would require Pelosi to change her mind. Instead, Pelosi may ask the House to vote on a resolution endorsing further investigation of Trump.

Rep. Sheila Jackson Lee, D-Texas, a member of the Judiciary Committee, told NBC News that she is drafting a resolution with that aim — and Democrats say it has been raised with Pelosi — that could be introduced as early as Wednesday.

She said her resolution would be one of "solidarity and significance that deals with the idea of moving forward" on investigations rather than impeachment.

"The caucus is in a position of believing that there is lawless behavior going on," she said. "We have not had a full discussion of this issue of impeachment, but I do think we have a full commitment on the issue of investigations and I think that is where we are and many others are raising the call for impeachment, but they are still working with the team on how best to reach that."

Parting with several of the most liberal members of her committee is no small matter, and it is a strong signal that the loudest voices on the panel don't speak for everyone.

Likewise, Rep. Judy Chu, D-Calif., who serves on the Ways and Means Committee, which has watched the administration block its effort to obtain Trump's tax records, said she's not ready to go down the impeachment road in part because the process of using the courts to mediate the dispute between the executive and legislative branches hasn't played out yet.

She said she was encouraged by a federal judge's decision this week to order the production of Trump financial records for the Oversight and Government Reform Committee, a ruling that upheld broad investigative powers for Congress.

"I want to see what happens with the rest of the testimonies that have been requested. I want to see what happens with the documents that should be produced," she said. "I also want to see what our court action will produce."

For impeachment to be successful, the American public has to be supportive, she said, and "more needs to be developed" for that to happen.

But Rep. Jackie Speier, D-Calif., who said the sentiment in the caucus is shifting toward impeachment, said the point isn't to oust Trump through congressional action.

"Let me be clear: I don’t believe that in the end we will do any more than lay out for the American people the articles of impeachment and then rather than send it to the Senate where he would be tried, I think the trial will be the 2020 election and the American people can convict him," she said.

Asked whether she backed starting an inquiry now, Speier responded by sticking one of her thumbs up in the air.

For Pelosi, the trick is finding a move that isn't too slow for her impeachment hawks and isn't too fast for her politically vulnerable members. She may wind up disappointing her political base and leaving lawmakers who need Republican votes to win re-election exposed to GOP criticism.

As Kennedy noted, it's not easy keeping her caucus moving in the same direction at the same speed.

"Tough job," he said.