President Donald Trump abruptly stalked out of a meeting with congressional leaders Wednesday with a flat declaration he would no longer work with Democrats unless they drop all investigations in the aftermath of the special counsel's Trump-Russia report.

Democrats said the walkout seemed scripted. House Speaker Nancy Pelosi called it all 'very, very, very strange' and said she was praying for Trump and the nation.

After turning and leaving the three-minute non-meeting with the Democratic leaders, scheduled for a discussion of US infrastructure problems, Trump strode to the Rose Garden where aides had gathered reporters and TV cameras for his demand that Congress drop its investigations that are increasingly leading to talk of what he called the 'i-word' -- impeachment.

Trump assailed Pelosi in particular for her comment earlier in the morning on Capitol Hill that she believed the president was engaged in a 'cover-up' of the Russia probe.

Trump said, 'I walked into the room and I told Leader Schumer and Speaker Pelosi I want to do infrastructure,' referring to the top Democratic senator, New York's Chuck Schumer.

'But you know what we can't do it under these circumstances,' Trump said. 'So get these phony investigations over.'

The president didn't shake anyone's hands or take a seat but spent three minutes contending he had been prepared to work on infrastructure, trade and other issue but now he couldn't because Pelosi said 'something terrible,' according to an administration official and another person familiar with what happened in the room. Trump then left before anyone else could speak.

Pelosi said to those still in the room — no Republican lawmakers were there — that she had known the president was not serious about infrastructure and would find a way out, according to another person familiar with the meeting.

Back on Capitol Hill, Pelosi said Trump 'just took a pass' on working on national infrastructure problems.

Pelosi, flanked by Schumer and other House and Senate leaders, said the Democrats had gone to the White House 'to give this president the opportunity to have a signature infrastructure initiative.' She said she would be praying for the president.

Trump tweeted back: 'and Nancy, thank you so much for your prayers. I know you truly mean it.'

The meeting at the White House had been set weeks ago after Trump and the Democratic leaders agreed to talk further about a possible $2 trillion infrastructure proposal. Trump was due to provide the Democrats with his ideas on how to pay for it. Schumer said when Trump 'was forced to say how he would pay for it he had to run away.'

Despite the sudden turn of events, the outburst followed a familiar script of Trump convening leaders at the White House only to try to turn the tables and refocus attention. He has stormed out of previous sessions.

Earlier Wednesday, Pelosi told reporters after a private meeting of House Democrats that Trump is 'engaged in a cover-up,' even as she tried to tamp down some Democrats' rush toward an impeachment inquiry in their showdown with the White House.

Pelosi and five of her top investigative committee leaders spoke with fellow Democrats after an increasing number called for the beginning of an impeachment inquiry following special counsel Robert Mueller's investigation into Russia election meddling and contacts with the Trump campaign.

Those Democrats say the move would not necessarily be aimed at removing the president, but instead to bolster their position in court as Trump has broadly stonewalled their investigations. Some two dozen House Democrats have signed on.

With her leadership team, Pelosi, who has resisted pressure to impeach, pointed rank-and-file Democrats toward the legal battles that she said have already found success in forcing Trump to comply with investigations.

'We do believe it's important to follow the facts,' Pelosi told reporters afterwards. 'We believe that no one is above the law, including the president of the United States, and we believe that the president of the United States is engaged in a cover-up — in a cover-up.'

A growing number of Democrats, incensed by former White House counsel Don McGahn's defiance Tuesday of a House panel's subpoena for testimony, have confronted Pelosi and pushed her and other leaders to act.

Pelosi has said she believes Trump is 'goading' Democrats into impeachment as a political tactic. And Trump appeared to relish the Democratic division in a Wednesday tweet: 'The Democrats are getting ZERO work done in Congress.'

Democrats leaving the meeting appeared to be taking Pelosi's words into consideration. Tennessee Rep. Steve Cohen, who called for the impeachment inquiry on Tuesday, said he could see both sides.

Of leaders' reluctance, Cohen said 'it's a political concern rather than an actual constitutional one.'

Rep. Katie Hill, a freshman from a California swing district, said she wants to let court actions play out a bit, and is undecided on starting an impeachment inquiry.

The more Trump 'defies us, the more that it's becoming an inevitability,' she said. 'But I don't think that the caucus as a whole is there yet.'

Some Democratic leaders, while backing Pelosi, also are signalling that a march to impeachment may become inevitable.

'We are confronting what might be the largest, broadest cover-up in American history,' Majority Leader Steny Hoyer told reporters Tuesday. If a House inquiry 'leads to other avenues including impeachment,' the Maryland Democrat said, 'so be it.'

But South Carolina Rep. Jim Clyburn, the No. 3 Democrat in the House, counselled caution. A majority of Democrats would support impeachment, he said, 'just not now.' He told CNN the House should follow a methodical process to get to the facts about Trump's actions.

Amid the impeachment talk and despite Trump's pledge to stonewall, there was one rate example of detente between House Democrats and the administration — intelligence committee Chairman Adam Schiff postponed a meeting to enforce a subpoena against the Justice Department after the department agreed to turn over a cache of documents related to Mueller's report.

Schiff said the department 'will begin turning over to the committee twelve categories of counterintelligence and foreign intelligence materials as part of initial rolling production.'

Still, Democrats are continuing to escalate their requests for information. The House Judiciary Committee recently voted to hold Attorney General William Barr in contempt of Congress after negotiations broke down with the department over similar materials.

On Tuesday, House Judiciary Chairman Jerrold Nadler issued subpoenas for more Trump administration officials — former White House communications director Hope Hicks and Annie Donaldson, a former aide in the White House counsel's office — for documents and testimony. The committee is expected to vote on contempt against McGahn in June.

McGahn is the most-cited witness in Mueller's Trump-Russia investigation report, recounting the president's attempts to interfere with the probe. And that makes his silence all the more infuriating for Democrats.

'Our subpoenas are not optional,' Nadler said. 'We will not allow the president to stop this investigation.'

Democrats are also encouraged by an early success in the legal battles, a Monday ruling by a federal judge against Trump on in financial records dispute with Congress. Trump's team filed a notice of appeal on Tuesday.

With a 235-197 Democratic majority, Pelosi would likely find support for starting impeachment proceedings, but it could be a tighter vote than that margin suggests. Many lawmakers come from relatively conservative districts where Trump also has support.