House Speaker Nancy Pelosi still isn't ready to impeach Donald Trump but 50 members of her Democratic caucus – and one lone Republican – are out for the president's political blood.

Outside liberal groups say it's time too, but even after special counsel Robert Mueller essentially called on Congress to pick up where his investigation left off, Pelosi isn't budging.

An NBC News reporter shared the network's latest head-count on Friday morning, noting that the 51 pro-impeachment lawmakers include 11 members of the powerful Judiciary Committee.

That's where any impeachment inquiry would begin.

But Pelosi is carrying on as she has since taking the speaker's gavel in January, promising the House will methodically pursue its investigations of Trump – wherever they lead.

What to do? Nancy Pelosi is facing more calls from her caucus to impeach Trump but believes it would be dangerous for the party's 2020 prospects to buckle to the pressure

Daring the Democrats: Rep. Adam Schiff, chairman of the House intelligence committee, said he's not urging impeachment yet, 'though the president seems to be doing everything in his power to get me there'

Unwelcome message: Greg Staton told constituents that he now backs impeachment, adding to the tide of pressure on Pelosi

This is her balancing act: toggling between mounting pressure from other Democrats and her own political instincts.

She's sticking with her plans for a more measured, 'ironclad' investigation that makes it clear to Americans the choices ahead. It's uncharted territory for the speaker, and this Congress, with both high risks and possible rewards ahead of the 2020 election.

Trump declared his own challenge on Thursday. He called impeachment a 'dirty, filthy, disgusting word' and said courts would never allow it.

'Many constituents want to impeach the president,' Pelosi acknowledged shortly after Mueller's remarks Wednesday. 'But we want to do what is right and what gets results.'

Her calculus is political as well as practical, knowing that even if Democrats in the House have the votes to approve articles of impeachment, the Republican majority in the Senate is hardly likely to vote to convict him.

Opinion polling does not favor impeachment, and a full-blown but failed effort might well help the president win re-election. Rather than go it alone, she is urging Democrats to build the case so the public is with them, whatever they decide.

'Nothing is off the table,' Pelosi said, 'but we do want to make such a compelling case, such an ironclad case.'

It has been this way for weeks. As more and more Democratic lawmakers -- and presidential candidates -- call for impeachment proceedings, Pelosi is urging restraint. Those around her say she's feeling no pressure.

On Wednesday, many Democrats took Mueller's words as an invitation to impeach.

House progressives like this group engaged in a pro-abortion protest last week are all in favor of impeachment – other than the gun-shy Pelosi

Mueller told the country, as he said in his 448-page report last month, that while charging the president with obstructing justice was 'not an option' under Department of Justice guidelines, he also did not exonerate Trump.

Instead, Mueller said, 'the Constitution requires a process other than the criminal justice system to formally accuse a sitting President of wrongdoing.' Without saying the word, Mueller was pointing to impeachment.

More presidential hopefuls -- Cory Booker, Kirsten Gillibrand and John Hickenlooper -- quickly called for impeachment proceedings. Half the Democrats on the House Judiciary Committee want an inquiry. And dozens of other House Democrats, not just the liberal left flank, are on board.

At a town hall meeting that night, Rep. Pramila Jayapal told voters in Seattle, said the road ahead 'weighs on me.' She is among those who want formal impeachment proceedings.

'Not everybody in the caucus is there yet, that is why Speaker Pelosi has a difficult role and she has been trying to figure out exactly how we will move forward,' she told the audience.

'The more the president obstructed justice ... the more certain we are going to be headed in a direction that I think many of us have already come out for -- and that is an impeachment inquiry.'

More joined Thursday, including Rep. Greg Stanton, a freshman congressman from Arizona who said, 'This conclusion will be unpopular with some, but it is the right thing to do.'

At a town hall in Henderson, Nevada, presidential hopeful Bernie Sanders, who favors impeachment, said, 'Nancy Pelosi does not have an easy job.'

But this isn't entirely new for her.

She witnessed the efforts to impeach Richard Nixon and Bill Clinton and, as speaker a decade ago, tamped down cries to impeach George W. Bush over the Iraq War.

Also, the voices for impeachment make up just a slim fraction of the broader Democratic majority in the House. Many of the others represent more conservative districts and face re-election where Trump has significant support.

Back home during a visit to a supermarket in Peoria, Illinois, Rep. Cheri Bustos fielded questions on health care and other issues, an aide said - but impeachment didn't come up.

Mic drop: Mueller's dramatic public statement Wednesday means the question of what to do with his investigation's findings and evidence is entirely in the hands of Congressional Democrats

In each other's hands: Nancy Pelosi and Donald Trump's political futures are entwined by the question of impeachment

Most of Pelosi's top lieutenants are following her lead.

Rep. Adam Schiff, chairman of the House intelligence committee, said Thursday in California he's not urging impeachment yet, 'though the president seems to be doing everything in his power to get me there.'

Schiff warned that impeachment is not a 'cure all.' He said, 'Impeachment doesn't remove this president. There is only one way to remove this president, and that's by voting him out of office.'

Six committees in the House are pushing ahead with investigations of Trump's actions -- his business dealings, his actions during the Russia probe, his running of the government -- and many of their inquiries are moving into legal battles where, so far, courts are siding with Congress against blocking efforts.

At the same time, the House is trying on other fronts to hold Attorney General William Barr and others in contempt of Congress for failing to comply with subpoena requests for documents and testimony.

The actions will test the Supreme Court's decision, some 100 years ago that Congress has an oversight role as part of the nation's system of checks and balances, in ways that could set precedent for years to come.

One Democrat on the Judiciary panel, Val Demings of Florida, a former police chief who favors opening an impeachment proceeding, explained in an earlier interview, that she and others are 'just trying to figure it out.'

'During the civil rights movement I'm sure the time probably wasn't right politically, but we did in our hearts what we knew was right,' she said.

With Mueller now unlikely to testify before Congress, Democrats are being denied a star witness who could focus Americans' attention in a high-profile way.

Billionaire Tom Steyer, a leading impeachment advocate, says time is narrowing for Pelosi to launch impeachment hearings before the 2020 political campaign.

For so long, Democrats were waiting for Mueller's report. Now, Steyer said Mueller has spoken and provided them the way forward. Rather than being risky, Steyer said in an interview Thursday, the politics are on the side for impeachment.

'Justin Amash got a standing ovation,' he said, referring to the Michigan Republican who broke ranks with the GOP and joined calls for impeachment. 'Americans like truth tellers. Americans like people who stand up for their values.'