WASHINGTON -- Rep. Adam Schiff, the ranking Democrat on the House Intelligence Committee, said Tuesday that there is "mounting concern" about how the Trump administration "appears to be interfering with the Russia investigation."
Schiff spoke to CBS News' Nancy Cordes shortly after reports that President Trump -- according to a memo then-FBI director James Comey wrote -- asked Comey to end an investigation into former National Security Adviser Michael Flynn.
"This is obviously a very serious charge -- the heart of which would be interference or obstruction of the investigation," Schiff, a former lawyer, said.
He said, however, that he would need to see more evidence before saying Mr. Trump's comments were obstruction of justice.
"I would need to look at just what the president said," Schiff told Cordes. "I would be interested to see if the notes said what the president said... but it's enough for the Congress to insist on the director coming back and obtaining this evidence."
Flynn was forced to resign in February after it became publicly known that he had several phone conversations with the Russian ambassador, despite having told the Vice President Mike Pence otherwise. The day after Flynn left his position, Mr. Trump met with Comey in the Oval Office and told him, "I hope you can let this go," according to the memo Comey wrote documenting their meeting.
The White House denies that Mr. Trump asked Comey to end the investigation.
Last week, Mr. Trump fired Comey, who had been leading the investigation into any connections between the White House and Russia. Comey had been set to testify in front of Congress about the investigation, and Democrats are now calling for Comey to testify. Schiff repeated the calls for Comey to testify.
Schiff, who has met with Comey often when he was the FBI director, said he and Comey did not have a "conversation ever about the president ever suggesting he drop the investigation."
Mr. Trump has indicated that there are tapes of his conversations with Comey, and Schiff said that if there are tapes, Congress needs to have them. Schiff said that if the notes from the Comey meeting exist, Congress needs to see them.
On Tuesday, Schiff and CIA Director Mike Pompeo held a previously-scheduled meeting. Schiff said he and Pompeo did discuss Mr. Trump'sto Russian officials, even though National Security Adviser Gen. H.R. McMaster insists Mr. Trump's comments were "wholly appropriate."