Story highlights Julian Zelizer: Comey shows Trump can't be trusted, even in private meeting with FBI chief

Other presidents lied, but Trump's problem differs in scale and scope, he says

Julian Zelizer, a history and public affairs professor at Princeton University and a CNN political analyst, is the author of "The Fierce Urgency of Now: Lyndon Johnson, Congress, and the Battle for the Great Society." He's co-host of the "Politics & Polls" podcast. The opinions expressed in this commentary are his own.

(CNN) Almost as soon as former FBI Director James Comey started his session with the Senate intelligence committee Thursday, he characterized the President and his White House as liars. Comey was not subtle. He said that the Trump team "told lies" when explaining why the President fired him.

He explained to senators that he kept careful notes about each encounter with the President because of his wariness about Trump. "I was honestly concerned he might lie about the nature of our meeting. It led me to believe I've got to write it down. ... I knew there might come a day when I would need a record of what would happen, not just to defend myself but to defend the FBI."

This was stunning to hear from a private citizen who was recently a high-ranking official in the executive branch. Comey was not saying that the President is someone who tends to be elusive or who uses words in tricky ways, but more fundamentally that he is a person who can't be trusted even in a private meeting with the head of the FBI.

It was such an extraordinary portrayal of the President that White House spokeswoman Sarah Huckabee Sanders had to tell reporters right away that "I can definitively say the President is not a liar, and I think it's frankly insulting that question would be asked."

Trump is not the first commander in chief to be called out for the veracity of his statements.

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