CNN had a problem. Donald Trump solved it.

It’s hard to imagine that either Trump or Zucker would be where he is today without the other. Trump’s foray into reality TV gave Zucker a prime-time hit when he badly needed one; now, Trump’s foray into politics has given Zucker a big story when he badly needed one. It’s a symbiotic relationship that could only thrive in the world of television, where the borders between news and entertainment, and even fantasy and reality, have grown increasingly murky.

In a sense, no one is better suited to navigate the terra incognita of Trump’s America than Zucker. He made his name in television by turning an ailing “Today” show into a $450-million-a-year juggernaut with a mix of news and stunts, like staging weddings in Rockefeller Center and putting Matt Lauer in a copy of the Versace dress that Jennifer Lopez wore to the Grammys. At NBC Entertainment, he helped usher in the age of reality TV, first with the gross-out show “Fear Factor” and then with “The Apprentice.” Now he’s running CNN at a moment when straight news has also become a form of entertainment.

Zucker likes to quote an early mentor at NBC, the late Tim Russert, considered by many the dean of the Sunday morning talk shows: “The primary responsibility of media is the accountability of government.” But Zucker is also using the power of his medium in a very different way than the network has used it in the past. CNN’s defining moments have historically involved another one of the responsibilities of journalism: bearing witness. The network’s cameras have illuminated the darkest corners of the world, recording history as it was being made, whether it was in Iraq, Tiananmen Square or flood-ravaged New Orleans.

What Zucker is creating now is a new kind of must-see TV — produced almost entirely in CNN’s studios — an unending loop of dramatic moments, conflicts and confrontations. “I’ve always been interested in the news, but I’ve always been interested in what’s popular,” Zucker says. “I’ve always had a little bit of a populist take on things. Which I know is interesting when you talk about Donald Trump.”