Fired FBI Director James Comey is now available to testify before Congress about his interactions with President Trump after speaking with Robert Muller, the special counsel leading the investigation of Russian election meddling, a source familiar with the matter told CBS News' Andres Triay.

Comey is expected to testify about his documentation of interactions with Mr. Trump, in which the president asked Comey for his loyalty and asked Comey to drop the investigation into former National Security Adviser Michael Flynn. The president reportedly told Comey, "I hope you can see your way clear to letting this go, to letting Flynn go. He is a good guy." Comey is not expected to testify about the details of the FBI's Russia investigation.

After his testimony, Comey will "continue to make himself available" to Mueller and investigators, according to the source.

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The Senate Intelligence Committee is aiming to have its hearing next week, although no date has been set. "The Committee welcomes the testimony of former Director Comey, but does not have an announcement to make at this time," Rebecca Glover, Burr's spokesperson, told CBS News.

Controversy surrounding Comey's firing continues to dog the White House. Meanwhile, the president is interviewing replacements for Comey, including two on Tuesday -- John Pistole, a former deputy FBI director, and Christopher Wray, a former assistant attorney general.

The White House claimed the president fired Comey for his mishandling of the Clinton email investigation, at the behest of memos from Attorney General Jeff Sessions and Deputy Attorney General Rod Rosenstein. But the president himself confused that message, telling NBC he thought of the "made-up" story about ties between his campaign and Russia when he fired Comey, and telling Russian diplomats firing that "nut job" Comey relieved great pressure on him from the Russia probe.

Comey's handling of the Clinton email investigation, however, entered the spotlight again last week after a report that a possibly fake Russian intelligence document, obtained by the FBI during the election, influenced Comey's decision to announce the end of the investigation. CBS News confirmed the existence of the document.