Comey has received invitations to testify from the Senate Intelligence Committee, the Senate Judiciary Committee and the House Oversight and Government Reform Committee. He has not yet stated publicly that he will appear.
The calls came as Congress began another chaotic day in the wake of news that the Justice Department had appointed Robert Mueller, a former FBI chief, as special counsel to probe possible ties between Trump's team and Russia.
The appointment lifted the pressure on many lawmakers, who found themselves under increasing pressure in the last month to support either an independent commission or special prosecutor to probe the Russia matter. Still, Mueller's appointment does not end the investigations already taking place on Capitol Hill, and lawmakers expressed a firm commitment to continuing their efforts.
Those efforts are taking place against a constantly shifting backdrop of news and controversy involving the Trump White House. Earlier this week, The Washington Post revealed Trump disclosed highly classified information to Russian officials during a meeting in the Oval Office. A day later, The New York Times reported Trump had pressured Comey to drop an investigation into former White House national security adviser Michael Flynn, based on a memo Comey wrote summarizing their meeting.
Congressional committees have sent multiple requests to the FBI and the White House to obtain any records of Trump's conversations with Comey. Among them was the House Oversight Committee, whose chairman appeared on television Wednesday night and disputed whether the Comey memo actually exists.
"I'm not even sure these memos exist," Rep. Jason Chaffetz, R-Utah, said in an interview with Fox News. "I'm not even sure they're real. I just don't know. . . . I do think it's worthy of investigation. I think they should pursue it."
Partisan differences also began to emerge on the matter of the special counsel.
While praising Mueller for being "as good as it gets," Chaffetz said he ultimately disagreed with the Justice Department's decision.
"They shouldn't have actually appointed somebody," he told Fox. "They're feeling the political heat. Maybe they're watching a little too much television and reading too many newspapers and whatnot."
He added that he had not seen "any evidence of actual collusion" between Trump associates and the Russian government.
"Where is the actual crime they think they need a special prosecutor to investigate?" Chaffetz said. "I haven't seen that."
The Senate and House Intelligence committees are the primary centers of investigation into the Russia matter on Capitol Hill. Chaffetz has been criticized for failing to use his power to investigative Trump.
Rep. Elijah Cummings of Maryland, the ranking Democrat on Oversight, called on Chaffetz to subpoena documents from the White House after the New York Times reported Trump's presidential transition team was aware of investigations into Flynn before naming him national security adviser.
"There is no longer any excuse to allow the White House to continue stonewalling," Cummings said Thursday in a statement. "The Chairman either needs to subpoena the White House or let the Committee take a vote."
Cummings elaborated in an interview with MSNBC's "Morning Joe."