Sen. Dianne Feinstein (D-Calif.) said Sunday that Congress should investigate whether former Attorney General Loretta Lynch pressured former FBI Director James Comey to cover for Democratic nominee Hillary Clinton's presidential campaign.

"I think we need to know more about that," Feinstein told host Brianna Keilar on CNN's "State of the Union."

"And there's only way to know about it, and that's to have the Judiciary Committee take a look at that," Feinstein, the top Democrat on the Senate Judiciary Committee, said.

Comey testified last Thursday that he felt "queasy" after Lynch asked him to characterize his probe into Clinton's emails as a "matter," rather than an investigation. He told the Senate Intelligence Committee that such a request would match the wording of Clinton's campaign.

Feinstein, who is a member of the Senate Intelligence panel, said she would've also felt queasy.

"I would have a queasy feeling, too, though, to be candid with you," the longtime Senate Democrat said.

She added that an investigation separate from the ongoing probe into Russian interference in the election is needed.

"I don't think we should mix the two," she added.

Feinstein said she has not yet decided from Comey's testimony whether President Trump's interactions with the ex-FBI director amount to obstruction of justice.

"I don't know whether it's obstruction of justice. I don't intend to draw any conclusions until investigations are finished," she added.

Trump on Friday denied that he asked Comey to let "go" of his investigation into former national security adviser Michael Flynn and that he requested Comey pledge his loyalty to him prior to Comey's dismissal.

The president added that he is "100 percent" willing to testify about his interactions with Comey under oath.