Paul Lee, the ABC programming chief who helped launched such series as “How to Get Away With Murder” and “Scandal,” is stepping down from the broadcast network, the network said, in what would appear to be the first effort by Ben Sherwood, the new head of Disney’s entertainment networks, to put his imprint on the operation.

ABC said Lee would be replaced by Channing Dungey, who previously supervised development of dramas, movies and miniseries at the network. She is the first African-American to hold the title of president of entertainment at one of the big U.S. broadcast networks. A report in the New York Times suggested that Lee clashed with Sherwood, who was named co-chairman of Disney Media Networks and president of Disney-ABC Television Group little more than a year ago.

“Leading ABC has been a fantastic experience. I’m especially proud of the incredible team I built and the strategic, creative vision we established and successfully executed for both the network and studio,” Lee said in a statement.

Lee joined ABC after a successful stint at ABC Family, the cable network now known as Freeform. Under his aegis, the network developed a slate of originals that appealed to young people too grown up for Disney Channel fare but not yet at the upper end of the 18-49 demographic spectrum desired by advertisers. Among the series Lee helped launch were “Kyle XY” and “Pretty Little Liars.” The network under his leadership also enjoyed the success of a stand-out series, “The Secret Life of the American Teenager.” Lee’s ascension to ABC Entertainment in 2010 was taken as evidence of the influence of cable — in which TV networks cater to a more narrowly defined audience drawn to a popular niche — on broadcast programming, which has typically been aimed at the widest swath of viewers possible.

ABC had a lot of momentum last season, riding its “TGIT” drama lineup and a slew of other hits like “Modern Family” and “Shark Tank” to a first-place finish among adults 18-49 for the May sweep. Since the fall of 2015, however, its performance has softened, with  numerous shows falling off and only “Quantico” giving much of a showing among the network’s freshman series. For the season, ABC currently ranks fourth in 18-49 and third in total viewers. As has been the case in recent years, ABC set some of its biggest-priority new shows to air in the days and weeks leading out of its telecast of the Oscars. Dramas “The Catch” and “The Family” and comedy “The Real O’Neals” will all premiere in March.

Lee and Sherwood had previously operated on a more even playing field. One was the head of entertainment programming at ABC, the other president of ABC News.

Yet Sherwood is known for taking a decidedly hands-on approach, and likely wanted to take a more direct hand in ABC operations. While he ran ABC News, he was famous for his attention to every element of “Good Morning America,” the ABC morning-news program that during his tenure usurped the No. 1 standing of NBC’s “Today” in the ratings. One feature of the “GMA” control room is an old-fashioned telephone receiver that gave ABC executives a direct line into the inner operations of the network’s flagship show. Sherwood was known to have made frequent use of the device.

A spokesman for ABC could not be reached for immediate comment.

He and Dungey will face interesting challenges in days ahead. Under Lee’s aegis, the network built up a reliance on producer Shonda Rhimes’ soapy dramas — “Grey’s Anatomy,” “Scandal” and more — along with a smart set of family comedies (“Black-ish” and “Fresh Off  the Boat”) that delve into multicultural family situations and a series of limited-run dramas (“American Crime,” “Wicked City”) that seek to compete with acclaimed cable entries like “Better Call Saul” or “The Americans.” They will have to determine the right ABC programming formula at a time when nabbing the large crowds upon which broadcast TV thrives has become exponentially more difficult.

ABC  is switching programming chiefs in the middle of development season, when TV networks try to cull what they think will be the best candidates for the next programming season. Already, ABC has picked up comedy pilots like “Pearl,”  about a dying family matriarch who seeks to control her clan, and “Speechless,” about a family with a special-needs child. The network has also picked up a pilot for “Model Woman,” inspired by the biography of model-agency doyenne Eileen Ford.

This isn’t the first time ABC has set in motion a surprise succession among its top programmers. Lee took the programming reins in 2010 from Stephen McPherson, an executive known to clash with his boss and Sherwood’s predecessor, Anne Sweeney. McPherson abruptly stepped down just a few months after ABC unveiled its schedule for the 2010-11 TV season and did upfront deals with advertisers based on the roster he had announced.