CNN's Brian Stelter suggested that Shepard Smith's abrupt departure from Fox News was politically motivated, claiming the 23-year network veteran "couldn't take it anymore."

Stelter suggested that Smith, who quit on-air Friday afternoon in a shocking goodbye segment, had tired of political adversaries on the cable news network.

"Together with my colleagues, we have written a first draft of history and endeavored to deliver it to you while speaking truth to power without fear or favor it in context and with perspective," Smith said on Friday. "I am eternally grateful for the opportunity. For handing me the breaking news reins as managing editor, senior correspondent, and chief news anchor for this news network, I am thankful and humbled."

Stelter, who is writing a book about Fox News, said during a Friday night appearance on CNN that Smith "left because he couldn’t take it anymore."

"Sources tell me that he was simply appalled by some of the opinion hosts’ comments," he told host Erin Burnett. "He felt that he had been marginalized. There wasn’t room for him anymore."

Stelter also reported on the matter in an article for the network.

"In September, according to a well-placed source, he went to Fox News management and asked to be let out of his long-term contract. Tensions with the opinion shows were getting to be too much," he wrote. "Executives at the network leaned on him to stay, but to no avail."