“Today” has to find a new leader to take it into tomorrow.

Jamie Horowitz arrived at NBC News in September from ESPN with a mandate to seize the reins of the unit’s venerable “Today” franchise and steer it to new frontiers, whether they be new-media venues or a return to the number-one spot among morning shows that was taken in 2012 by ABC’s “Good Morning America.” Now, in November, he is abruptly leaving the operation.

“He’s a talented producer and executive, but, together, he and I have come to the conclusion that this is not the right fit,” NBC News President Deborah Turness said in a memo Monday to staffers. In the wake of Horowitz’ departure, Turness said, she will continue working closely with Don Nash, the executive producer of “Today,” and Jen Brown, the vice president and general manager of Today.com. She expects to find a new general manager of “Today,” she said.

Horowitz’ quick departure could hinder NBC News’ continuing efforts at trying to return “Today” to the top spot it held among the cereal-and-coffee crowd for 16 years. His hire was meant to cap off a series of fortunate incidents at the program – the re-signing of veteran host Matt Lauer and the addition of Carson Daly to the anchor team.

Instead, “Today” staffers found Horowitz’ style “divisive,” and “destabilizing,” according to three people familiar with the program. One of these people suggested Horowitz may have been viewed by show staffers as too aggressive. He had recently been on a “listening tour,” this person said, visiting different staffers as well as people who had previously worked on the program.

A recent New York Post report that suggested Natalie Morales, the news anchor during “Today’s” 8 a.m. hour and a co-anchor of the show’s 9 a.m. hour, was being nudged along in favor of Tamron Hall, a 9 a.m. staffer whose presence across the show has been growing, has been viewed within NBC News as a by-product of Horowitz’ operating style, these people said. The insiders denied recent speculation that Horowitz was currying favor among senior executives at NBCUniversal or its owner, Comcast, in an effort to perhaps take Turness’ job.

Even so, the inability of  the two sides to play well may suggest something was amiss in the vetting process. NBCUniversal’s ability to bring Horowitz over from Walt Disney’s ESPN had been viewed as something of a coup. Horowitz was a vice president of original programming and production at the sports-cable juggernaut. In recent months, he helped launch “Conlin’s New Football Show,” a roost for anchor Colin Cowherd, and Keith Olbermann’s new program, both on ESPN2.

So interested was NBCUniversal in Horowitz that the company allowed Bill Wolff, the executive producer of MSNBC’s flagship primetime program, “The Rachel Maddow Show” and a supervisor of all of that network’s primetime programming, to defect to run ABC’s “The View” in exchange for Horowitz being let out of his ESPN contract early. Before that happened, Horowitz was not expected to join NBC until early next year.

“Jamie has the skills, the talent and the experience to lead the ‘Today’ brand into the future,” Turness said in a statement when Horowitz’ hire was announced.

Horowitz isn’t the first executive to try and shake up a close-knit media operation and receive a rebuke for his efforts. In 2011, Jack Griffin was fired from magazine giant Time Inc. then owned by Time Warner, after less than six months on the job.  Griffin was said at the time to utilize a top-down management style rather than the group decision making to which executives were accustomed. In a statement issued when Griffin left, Time Warner issued a statement saying that Griffin’s style “did not mesh” with the company’s. Griffin became chief executive of Tribune Publishing in April.

In the meantime, “Good Morning America” continues its winning streak. For the week of November 3, “GMA” notched 669,000 more viewers than “Today”‘ 159,000 viewers in the demographic advertisers seek from news programs, people between 25 and 54; and 18,000 viewers between the ages of 18 and 49.

The NBC morning show “has great momentum and is closing the ratings gap. The exclusives keep coming and there is a great energy both on- and off-air, and in digital and social,” Turness said in the memo. “My focus – as always – is to support this special brand and its amazing and dedicated staff, and to position it for continued success.”