"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," reports CNN's Brian Stelter. "Tensions with the opinion shows were the breaking point. Executives at the network leaned on him to stay, but to no avail. On Friday afternoon he announced his departure on the air, then exited the building immediately, clearly emotional about saying goodbye to his television home of twenty years." Stelter, host of CNN's Reliable Sources, adds that "for months I have been working on a book about Fox News in the Trump age. Staffers have been confiding in me about the challenges of covering the news inside a network that is increasingly defined by sychophantic pro-Trump personalities like Sean Hannity. Staffers on the news side unanimously point to Smith as a role model. But 'it was clear he wasn't happy, on air and off air,' one of the staffers said after Friday's stunning resignation announcement. Two other staffers also said he'd indicated he 'wanted to leave -- meaning that he was not forced out by management, as some outsiders immediately speculated on social media." ALSO: Why Smith's Fox News exit is likely a bigger deal than you realize.