Sen. John McCain, R-Ariz., expects Congress' investigation into President Trump and Russia to reveal additional, unprecedented details about both parties.

"There's a lot of things about our relations with Russia that trouble me a lot," McCain told CNN's "State of the Union" host Jake Tapper on Sunday morning. "There's a lot of aspects of this whole relationship with Russia and Vladimir Putin that requires further scrutiny, and so far I don't think the American people have gotten all the answers. In fact, I think there's a lot more shoes to drop from this centipede."

The 2008 GOP presidential nominee said a number of Trump's campaign and transition associates need to be called to testify by the House and Senate intelligence committees, including Roger Stone.

Stone has claimed to know Guccifer 2.0, the hacker supposedly behind the release of Democratic National Committee emails last summer. Stone also said he corresponded with WikiLeaks founder Julian Assange during the election.

"Obviously I think [Mr. Stone] and others need to be questioned," McCain said. "This whole issue of the relationship with the Russians and who communicated with them and under what circumstances clearly begs — cries out for an investigation."

McCain, who has been a critic of Trump's foreign policies since the president took office in January, warned the public to withhold its judgment until the investigations are completed.