Sen. Mark Warner, the top Democrat on the Senate Intelligence Committee, called for former White House chief strategist Steve Bannon to testify before the committee, after an excerpt from a forthcoming book revealed Bannon said a meeting between President Trump’s son and Russians was “treasonous” and should have been reported immediately to the FBI.

“I think Mr. Bannon should testify either before us or before Mr. Mueller,” Warner, D-Va., said. “Clearly if he’s going to make these kind of allegations, I would like to know under what basis.”