Members of key congressional committees pledged Sunday to proceed with aggressive investigations into Russia's meddling into the U.S. election and any ties with the Trump campaign, saying the American people need a full airing as to why former FBI director James Comey was ousted.

Comey was fired by President Donald Trump earlier this month. The former director agreed to testify before the Senate intelligence committee after the Memorial Day holiday.

Republican Sen. Marco Rubio of Florida, a member of that committee, said he wants to press Comey as to whether he ever believed the White House was interfering with his work, in light of a spate of news reports that Comey had kept detailed records of his interactions with Trump.

The New York Times reported last week on a Comey memo indicating Trump had urged him to drop an investigation into former national security adviser Michael Flynn. Separately, another Times report said Trump had told Russian officials in a closed-door meeting at the Oval Office that firing Comey "had relieved great pressure on him."

"Did he keep these memos? What do those memos say? And why did he write it? And how did he feel? Did he ever feel like he was being put in a position where he couldn't do his job?" Rubio asked. "There's no doubt that that's the questions that are going to get asked, and asked repeatedly."