"Until the Administration fully explains the facts of this case, the American people will rightly doubt if their president can handle our nation's most closely kept secrets," Schumer said on the Senate floor.
Meanwhile, members of the House Intelligence Committee prepared to discuss the situation with CIA Director Mike Pompeo on Capitol Hill. The briefing, while previously scheduled, will be the first chance for committee lawmakers to question Pompeo as a group since Trump's disclosure was revealed.
A Republican former Marine intelligence officer now serving in the House said transparency demands the release of the Russia meeting transcript to the intelligence committees, if it exists.
"As an intelligence officer by training, I know firsthand the life and death implications of safeguarding classified information," Congressman Mike Gallagher tweeted.
"Our allies and partners must have the utmost confidence that sensitive information they share with us will not be disclosed," he wrote.
And in a sign of the issue's political potency, Republican Congresswoman Barbara Comstock issued a strongly worded statement criticising Trump and demanding more information.
"Once again we are faced with inexplicable stories coming from the White House that are highly troubling," stated Comstock, whose northern Virginia district went for Hillary Clinton by 10 percentage points in November.
"We need to have immediate classified briefings on what occurred at this meeting so that Congress can at least know as much as Russian leaders."
Trump tried to explain away the situation in a series of tweets, writing that he had the "absolute right" to share "facts pertaining to terrorism" with the Russian officials. The move contradicted Trump's own team, which had tried to contain the story yesterday by insisting that it was false.
Later, the White House national security adviser, Lieutenant-General H.R. McMaster, defended Trump's conversations as "wholly appropriate," but he declined to discuss whether the information shared by the President was classified.
Lawmakers' requests for more information portend a difficult week for the White House on Capitol Hill, where Republicans are seeking to maintain focus on their legislative agenda, including the negotiation of a Senate healthcare bill.
Senate Majority Leader Mitch McConnell who declined to comment yesterday on Trump's disclosures, said today that he wished the White House would produce "less drama".
"I think it would be helpful if the President spent more time on things we're trying to accomplish and less time on other things," McConnell said in an interview with Bloomberg News.
He continued to dodge questions about the story, first reported by the Washington Post, that Trump shared highly classified intelligence with Russia.
"I've heard the allegation. I've heard the response. I don't think I have anything to add," he told Bloomberg.
Lawmakers expressed shock and concern yesterday at the news of Trump's disclosures, which jeopardised a critical source of intelligence on Isis (Islamic State), according to current and former US officials.
"Clearly if there is some kind of a readout from that meeting and a transcript, that means there's probably a tape. We need to get a hold of that," Senator Amy Klobuchar, a member of the Senate Judiciary Committee, said at an event hosted by the liberal Centre for American Progress.
The event, which featured speeches by an array of Democratic lawmakers, revealed the left's growing frustration with the slow pace of investigations into Trump's alleged ties to Russia.
One audience member asked Senator Elizabeth Warren why lawmakers can't just say Trump obstructed justice when he fired Comey last week with the "Russia thing," as he later admitted, on his mind. "When can we call a spade a spade?" the audience member asked.
"I think we start by putting in place the tools for an investigation," Warren said. "We'll see where it takes us. If there's nothing there, so be it. If there is criminal activity there, then we're ready for the next step."
Several Republicans called for immediate briefings from the Trump Administration.
"The Administration should promptly share with Congress, in a classified setting, the precise details of the President's meeting," Congressman Justin Amash, a libertarian-leaning iconoclast who frequently breaks with his party, wrote on Twitter.
"Although the President has the legal authority to disclose classified information, it would be very troubling if he did share such sensitive reporting with the Russians," Senator Susan Collins, a centrist, said.
Even Republicans from Trump-friendly districts called for more information from the White House.
"[The] media reports are deeply concerning," tweeted Congressman Frank LoBiondo, whose New Jersey district swung strongly towards Trump in November. "Classified intelligence is classified for a reason and must be respected and protected as such at all levels of government."
