Earlier this week, revelations that Comey kept memos detailing his conversations with Trump, including one in which the president apparently pressed his former Federal Bureau of Investigation director to drop the inquiry into former national security adviser Michael Flynn, roiled Washington.
"I am hopeful that he will clarify for the American people recent events that have been broadly reported in the media", committee Chairman Sen.
Democrats, who have compared the widening scandal to the Watergate break-in and cover-up that brought down Republican former President Richard Nixon in 1974, were quick to pounce on the latest reports.
Committee leaders said on Friday he would appear sometime after the US Memorial Day holiday on May 29.
Sen. Lindsey Graham, R-S.C., who chairs a Judiciary subcommittee panel that has been driving much of the Russian Federation probe, echoed Grassley's and Feinstein's frustrations, and said he was "surprised" Comey would agree to testify at all, "given the fact that we now have a Special Counsel who will likely be investigating matters related" to his conversations with Trump. "I also expect that Director Comey will be able to shed light on issues critical to this Committee's investigation of Russian interference in the 2016 election".
Comey will certainly be asked about encounters that precipitated his firing, including a January dinner in which, Comey has told associates, Trump asked for his loyalty.
The New York Times is reporting that in a May 10 Oval Office meeting with Russian Foreign Minister Sergey Lavrov and Russian Ambassador Sergey Kislyak, President Trump referred to fired FBI Director James Comey as a "nut job" and told the two men that "I faced great pressure because of Russia".
Amid growing pressure, Rosenstein, the deputy attorney general, appointed former FBI Director Robert Mueller as a special counsel to oversee the Department of Justice's Russian Federation investigation.
"It makes it very clear that what Donald Trump was trying to do was to end the Russian investigation".
But Trump's conversations with Comey and the Russians were part of a pattern that could open him up to charges of obstruction of justice, experts say.
President Donald Trump has been narrowing a short list and interviewing candidates to replace FBI Director James Comey, whom Trump fired on May 9.
The Times said the quotes were read to them by one American official and a second official confirmed what it called broad outlines of the discussion.
Trump's Oval Office meeting with Russian Foreign Minister Sergey Lavrov and Russian Ambassador to the US Sergey Kislyak came one day after Comey was sacked.
Reports of a memo said to have been written by Comey details the former FBI director's discomfort during a meeting with the president in which he asked Comey to "let it go" in regards to the investigation of former National Security Adviser Michael Flynn.
The White House press secretary, Sean Spicer, said in a statement on Friday that "by grandstanding and politicizing the investigation into Russia's actions, James Comey created unnecessary pressure on our ability to engage and negotiate with Russian Federation".
As Trump embarked on his first foreign trip, the Times fired another shot. "As I said, Nixonian", said Sen. But lawyers in the White House counsel's office have consulted experts in impeachment during the past week and have begun collecting information on how such proceedings would work, a person briefed on the matter told CNN. Rosenstein said that though he was personally fond of Comey, "I thought it was appropriate to seek a new leader". "That's taken off, '" Democratic senator Patrick Leahy said on Twitter.
He says that even his "enemies" recognize his innocence, and he's declaring himself the most unfairly hounded president in history. "I don't think (Rosenstein) did a lot to bolster our confidence in him today".
Deputy Attorney General Rod Rosenstein was returning to the Capitol on Friday for another closed-door session, this time with all members of the House.