On Oct. 22, 2016, Donald J. Trump made his own history in Gettysburg, Pennsylvania, where he was holding a campaign rally just weeks before his election.

“AT&T is buying Time Warner, and thus CNN,” he told his audience, calling the proposed merger an example of a media “power structure” that was working to suppress his vote and the voices of his supporters. It was, he said, “a deal we will not approve in my administration.”

He specifically cited media concentration. But his singling out of CNN in the context of an alleged plot against him was lost on no one.

Now, CNN is at the heart of a dispute between the Justice Department and AT&T and Time Warner. Three people from the companies said Wednesday that the department insisted that AT&T divest either CNN’s parent company, Turner Broadcasting, or its valuable DirecTV service in return for approval.