WATCH: Bob Woodward reveals the key to proving Trump's complicity in the Jan. 6 MAGA riot

On CNN Monday, famed Watergate reporter Bob Woodward broke down the significance of retired Lt. Gen. Keith Kellogg, a longtime ally of former President Donald Trump, to helping the House committee investigating the January 6 attack on the U.S. Capitol.

"Keith Kellogg ... is somebody who is a Trump loyalist, but also an institutionalist," said Woodward. "He used to say within the White House that Trump and Pence, the vice president, were fire and ice. You can guess who was fire, Trump, and Pence was ice."

"Kellogg, as we found from multiple first-hand witnesses, was with Trump on January 6th, in the office with Trump, begging Trump to tweet out to stop the violence, and he said memorably, 'Mr. President, not everyone is carrying a television on their shoulder,' says go out and tweet, and this is a mob and when you have a mob, you have lost it,'" said Woodward.

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"Trump would not respond, and so Kellogg went to find Ivanka Trump, Trump's daughter, and she went to see Trump, her father, in the Oval Office dining room three times from multiple witnesses, and one of the things she said to President Trump is, let this thing go. Eventually he did tweet but it was delayed," added Woodward.

"So in a sense, from the point of view of an investigation, having somebody like Keith Kellogg there who was a participant, who is now under oath, you couldn't get a better witness. It's somebody that Republicans would have to look at and say, wait a minute, this is a credible strong person, somebody who served in the military for decades."

Watch below:

Bob Woodward on Keith Kelloggwww.youtube.com