"No one is above the law," the Speaker told reporters in the U.S. Capitol.
Inside the closed door meeting with fellow Democrats, Pelosi reportedly said that Democrats had reached 'a moment of truth' in terms of confronting President Trump.
The action by Speaker Pelosi came as pressure built from within the ranks of Democrats in Congress, as many made clear the last straw was that President Trump had reportedly leaned on the leader of Ukraine to investigate Joe Biden's family, mainly his son Hunter, who had done business in Ukraine.
Democrats also denounced the Trump Administration for withholding the details of a whistleblower complaint from inside the U.S. Intelligence Community, a move which Democrats said clearly violated federal law.
On the Senate floor, it was clear that the refusal of the Administration to turn over the complaint had left Republicans uneasy - as the Senate unanimously approved a resolution asking for the whistleblower documents.
"The only reason for any Senator to object would be to shield the President’s conduct from scrutiny by the public and the representatives they elected to represent them," said Senate Democratic Leader Charles Schumer.
Democrats said the contents of the whistleblower complaint were much more important than the transcript of a phone call between President Trump and the leader of Ukraine, which Mr. Trump said would be released on Wednesday.
"It’s not about the transcript of a call," said Rep. Justin Amash (I-MI), who left the Republican Party over the President's actions.
"Don’t let President Trump or Republican officials distract you with a straw man," Amash said. "It’s about his continuing abuse of the office of the presidency."
Under federal law, the whistleblower complaint by now should have been in the hands of both the House and Senate Intelligence committees for their review.
But the Acting Director of National Intelligence, Joseph Maguire, along with the Justice Department - have refused to do that.
Maguire is scheduled to testify on Thursday before the House Intelligence committee. Democrats said there will be more fireworks and controversy if Maguire continues to refuse to hand over the document.
Republicans denounced the move by Democrats.
“Speaker Pelosi’s much-publicized efforts to restrain her far-left conference have finally crumbled,” said Senate Majority Leader Mitch McConnell.
“This is just another in a long list of fake controversies they want to focus on,” said Rep. Bob Gibbs (R-OH).
“Until the full House votes to authorize an inquiry, nobody is conducting a formal inquiry,” said Rep. Doug Collins (R-GA).
In New York for a meeting of the United Nations General Assembly, the President had his own reaction.
“PRESIDENTIAL HARASSMENT!” he tweeted.