Rupert Murdoch’s announcement last month that he was naming his eldest son, Lachlan, chairman and C.E.O. of New Fox—the downsized media conglomerate that will control the news and sports assets the Murdochs aren’t selling to Disney—was the culmination of a long-deferred dream. When Lachlan joined News Corp in his early twenties, Rupert considered him to be his rightful heir. (He once described Lachlan as “the first among equals,” much to the frustration and pain of siblings James and Elisabeth). Lachlan quit in 2005 and returned to Australia after feeling Rupert undermined him in management disputes. Afterward, Rupert commenced a long courtship to win Lachlan back. But having repaired his relationship with Lachlan, Rupert seemed to echo the very mistake that led him to walk away.

In recent weeks, according to two highly placed sources, Rupert meddled in one of Lachlan’s first management decisions as C.E.O. Sources say Lachlan wanted to oust Fox News co-president Jack Abernethy, as part of a management overhaul of Fox News. The two have history: after Lachlan left in 2005, then-Fox News C.E.O. Roger Ailes put Abernethy in charge of the Fox Television Stations group, a division Lachlan had controlled. “This was Lachlan’s revenge,” one former executive said. After Lachlan told Abernethy he was out, Abernethy appealed to Rupert and “begged for his job,” the former executive told me. Rupert, who loves to wield power but dislikes open conflict, assented by telling Abernethy he could stay and run the station group—effectively a demotion—and relocate from New York to Los Angeles. (After this article was published, Lachlan Murdoch emailed to say the story was “total horseshit.”)

In many ways, it’s not surprising that the 87-year-old Rupert is refusing to allow Lachlan, 46, to reign unfettered. Over the last five months, Rupert has been recovering from a serious back injury that left him homebound after he fell on Lachlan’s yacht and is looking for ways to demonstrate to colleagues that he’s still vital. Rupert recently hosted entertainment-industry swells at a dinner at his Bel Air estate for Saudi Crown Prince Mohammed bin Salman. And in April, Rupert called Jared Kushner to get a last-minute invite to the White House’s state dinner for French president Emmanuel Macron (Murdoch’s spokesperson denied Rupert called the White House for an invite at the time).

Rupert’s meddling is not the only headache that Lachlan is dealing with as C.E.O. The crown jewel of New Fox—Fox News—is confronting some business headwinds. While Fox News dominated the ratings in May—a fact Trump bragged about on Saturday—the network is having new difficulties monetizing its most pro-Trump programming. According to three sources briefed on the numbers, advertising revenues for Sean Hannity and Laura Ingraham are down in recent months. “The pro-Trump thing isn’t working. We can’t monetize DACA and the wall and that right-wing shit,” one staffer said. “Despite all the hype on Hannity, they can’t sell it,” another insider told me. (Tucker Carlson’s show is faring better, sources said).

Through a spokesperson, Fox News president of ad sales Marianne Gambelli said: “Fox News is in the middle of a record year both in ratings and ad sales and Sean Hannity and Laura Ingraham have the highest rated shows in cable news.”

This story has been updated to include a comment from Lachlan Murdoch.