Three people with direct knowledge of the situation say that Chris Licht, a veteran television producer who helped create MSNBC and later retooled morning and late-night programming at CBS, is set to be the next leader of CNN.

Jeff Zucker, the CNN president who resigned over a romantic relationship with a colleague, is expected to be succeeded by Mr. Licht, who is currently the executive producer of Late Show with Stephen Colbert.

He is expected to join the network once WarnerMedia completes a merger with Discovery. The chief executive of Discovery and Mr. Licht have known each other for more than a decade.

A formal announcement is expected this week. The news of Mr. Licht's selection was first reported by Puck.

It would be the biggest challenge of Mr. Licht's career in television if he were to take over CNN. At a time of turmoil, he is joining the network.

The newsroom was roiled by the sudden departure of Mr. Zucker. Its prime-time and morning ratings are in third place behind Fox News and MSNBC. The future direction of the network has been raised by the impending takeover by Discovery.

The hugely successful MSNBC franchise that still dominates that network's morning lineup is co-created by Mr. Licht. He was credited with turning around the fortunes of CBS News when he joined in 2011.

The Late Show with Stephen Colbert had struggled in its early months to gain viewers and the critical praise enjoyed by its predecessor, David Letterman.

Mr. Colbert was encouraged to engage with current events and political news by Mr. Licht. He added live shows after State of the Union speeches and election nights. In the ratings, Mr. Colbert had beaten NBC's The Tonight Show five years in a row.