Washington (CNN) Political analyst David Gergen delivered a harsh critique of President Trump's campaign-style rally Saturday night in an appearance on CNN's "Newsroom."

"To bring your campaign speech into the presidency is something presidents rarely do," said Gergen, who has been a White House adviser to four presidents. "This was the most divisive speech I've ever heard from a sitting American president."

.@David_Gergen: "This was the most divisive speech I've ever heard from an American president" https://t.co/0yZZlMX2f1 — CNN Newsroom (@CNNnewsroom) April 30, 2017

Trump's delivered a rousing address to a crowd of supporters in Harrisburg, Pennsylvania instead of attending the White House Correspondents' Association dinner in Washington. The nearly-hour long speech began with attacks on the press and covered his tax plan, jobs, the yet-to-be-built wall, trade and other topics Trump had touted throughout his 2016 campaign.

"He played to his base and he treated his other listeners, the rest of the people who have been disturbed about him or oppose him, he treated them basically as 'I don't care, I don't give a damn what you think, because you're frankly like the enemy,'" said Gergen. "I think it was a deeply disturbing speech."