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Democrats pounced Tuesday night after a bombshell report that President Donald Trump asked FBI Director James Comey to halt his probe of Mike Flynn, with Senate Minority Leader Chuck Schumer saying the country "is being tested in unprecedented ways."

"In a week full of revelation after revelation — on a day when we thought things couldn’t get any worse, they have," Schumer said on the Senate floor. "I say to all of my colleagues in the Senate: History is watching."

Trump asked Comey to ease off an investigation into Flynn, Trump’s former National Security Adviser, according to a memo that the FBI chief wrote to his own files shortly after speaking with the president, NBC confirmed. The story was first reported by The New York Times.

Rep. Jason Chaffetz, R-Utah, chairman of the House Oversight Committee and who recently announced his retirement from Congress, said that “on the surface that seems like an extraordinary use of influence to try to shut down an investigation.”

"If the memo exists, I need to see it and I need to see it right away. We are drafting the necessary paperwork to get the memo so we will find out in a hurry if it’s out there," Chaffetz told NBC News.

Later in the evening, he wrote to the acting director of the FBI seeking the memo and related information saying that if Comey's allegation is true, it indicates Trump may have sought "to influence or impede" the FBI investigation of Flynn.

Related: Oversight Committee Chair Chaffetz Demands All FBI Documents on Trump, Comey

Sen. John McCain, R-Arizona, reportedly said at a dinner Tuesday night that the controversies have reached a "Watergate size and scale," according to Daily Beast correspondent Tim Mak.

McCain spokeswoman Julie Tarallo later said "Senator McCain's comments tonight were simply meant to convey that the constant revelations of events surrounding Russia's interference in the 2016 election are reminiscent of past scandals, are not good for America, and require further scrutiny."

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Tarallo said McCain continues to call for a select committee to investigate alleged Russian interference and all the events surrounding it.

Rep. Carlos Curbelo, a Republican in a swing district in Florida, had harsh words for the White House.

"If this is true, it is disconcerting and it opens up a new chapter of scandal and controversy in this country," he said.

Lawmakers in both parties said Comey must come and testify before Congress.

"Of course Director Comey should testify. I believe an open, transparent government is most effective for the people we represent," said GOP Rep. Cathy McMorris Rodgers, a member of the House leadership team.

Sen. Chuck Grassley, an Iowa Republican who chairs the Judiciary Committee, said he is determined to find out more about what's been going on.

"These latest reports further underscore the need for us to get a better understanding of the events that led to Michael Flynn's removal.

"Acting FBI Director Andrew McCabe testified that there has been no effort to impede the FBI’s investigation, which seems in conflict with the reports about a Comey memo," he added. "As I’ve said before, we need to get the facts out in the open, and that includes getting answers to our questions to the FBI and reviewing any memos related to the matter."

Sen. Jeff Flake, R-Arizona, said on Twitter: "Congress needs to see the Comey memo."

But Sen. Richard Burr, R-N.C., chairman of the Senate Intelligence Committee, was skeptical of the report.

"As close as (Sen.) Mark Warner and I have worked with the director over the past many months now, I actually believed the director might have told us if there had been a request like that (from Trump). And it was never mentioned by him," Burr told reporters, adding that he and Sen. Warner, the top Democrat on the committee, met with Comey the day before he was fired.

"I'm getting really, really tired of anonymous sources," Burr added.

A spokesperson for Burr said that while the committee hasn't seen the memo mentioning Trump's attempt to halt the investigation, "It certainly raises questions and he will follow up on acquiring those facts from credible sources."

The news comes 24 hours after a report that Trump allegedly revealed classified information to Russian Foreign Minister Sergei Lavrov and Russian Ambassador Sergey Kislyak during a meeting in the Oval office last week.

Sen. Lindsey Graham, R-S.C., who has been withholding judgment of Trump’s meeting with Lavrov, said that this is now more reason for Comey, who was fired exactly one week ago, to come testify.

"If Comey is alleging president did something inappropriate, there is an open invitation for him," Graham said. “Don't want to read it in a memo, I want him to say in person."

The latest developments have renewed focus on Democrats’ call for a special prosecutor to conduct an investigation.

"This stunning, breathtaking revelation that the president is accused of reaching out directly to the head of the FBI to stop an investigation on General Flynn under these circumstances raises serious questions of obstruction of justice," Senate Democratic Whip Richard Durbin said.