It would appear that Les Moonves is more difficult to replace than Shari Redstone and the rest of the CBS board anticipated when they orchestrated his defenestration as C.E.O. last September. “There clearly is no reasonable facsimile to Leslie, in terms of talent and reach and combination of skills,” someone who has been closely observing the succession drama told me recently. “Worse, people that come close to it are not willing to jump into the mix. They’re not.”

About six months ago, CBS hired head-hunting firm Korn Ferry to find a permanent replacement for Moonves, who was publicly accused last July of several #MeToo atrocities dating back more than a decade. (Moonves has referred to the “appalling accusations” as “untrue.”) Once the allegations about Moonves surfaced publicly, the CBS board moved swiftly to remove him from his position and to install Joe Ianniello, Moonves’s longtime No. 2, as the acting C.E.O. of the company. Although CBS put no “official” timeline on finding a successor, the board’s hope was to find a permanent C.E.O. by the end of March, sources say. But the end of March has come and gone, and there has been no announcement about who will replace Moonves. And CBS would prefer that there be as little focus as possible on that fact. Dana McClintock, CBS’s head of communications, declined to comment about the succession process, or where it stands.

But people familiar with the C.E.O. search tell me that there are two obstacles that the top candidates in the industry seem unwilling to tackle. One is the allegedly sexist culture at CBS, which transcends Moonves and seems to have pervaded the company, if the leaks are to be believed about the audit that two white-shoe New York law firms prepared—but never delivered in written form—for the CBS board. Fixing a damaged culture can be a difficult challenge for any executive. But doing so while also divining a strategy to enable CBS to compete more effectively against its better-capitalized peers at Comcast, Disney, Apple, and Amazon, to name a few, can be downright intimidating.

The second obstacle is Shari Redstone, the mercurial 64-year-old daughter of billionaire media mogul Sumner Redstone, who has literally taken control of both CBS and Viacom in the wake of her ailing father’s physical and mental incapacitation. (Sumner will be 96 next month.) Since 2016, Shari has twice tried (unsuccessfully) to remerge CBS and Viacom, despite her father deliberately separating them into two publicly traded companies in 2006. She has replaced the Viacom C.E.O. and installed Bob Bakish, a loyalist, and also replaced much of the Viacom board of directors. Following Moonves’s departure last September, she has followed the same script at CBS. Multiple CBS board members have been her selections. To complete her coup, Shari has been desperately seeking a CBS chief executive whose loyalty to her is unquestioned. Ultimately, that could be Ianniello’s biggest obstacle in trying to get the job on a permanent basis. He has done his best to put the Moonves era behind CBS, and has made several important personnel decisions—for instance, installing Susan Zirinsky as head of CBS News—that have been popular internally. But while he has done his best to show his fealty to Shari, she may not be able to overcome the fact that Moonves wanted Ianniello, whose current contract ends in June, to succeed him.

Bakish also wants the job—and Shari wants him to have it. But a Bakish appointment probably could not happen unless CBS and Viacom are recombined, which is unlikely to happen soon. As part of a September settlement with Moonves, Shari agreed that National Amusements, the Redstone family holding company that controls about 80 percent of the voting stock of both CBS and Viacom, would not reinitiate merger discussions for roughly two years. (The settlement, cleverly, did not prevent the boards of CBS and Viacom from initiating merger discussions, which have reportedly already begun.) Shari’s stated preference for Bakish may also be dissuading talented outsiders from taking on the CBS conundrum. Why bother if it’s just going to be merged with Viacom, with Bakish in charge of the merged entity? “The problem that Shari has is that people who pass the smell test, in terms of loyalty, aren’t always the A+ talent,” the close observer noted. (A spokeswoman for Shari declined to comment on the CBS succession plan.)