Protesters from the National Organization for Women of New York in front of News Corp. headquarters Thursday, the morning after Fox News cut ties with host Bill O’Reilly. (Timothy A. Clary/AFP/Getty Images)

With Bill O’Reilly’s ouster from Fox News Channel, the hard part may be over for the scandal-scarred network. Now the harder part begins.

Fox’s abrupt termination of O’Reilly’s contract on Wednesday puts the leading cable-news network in rebuilding mode, beset by uncertainty. Will O’Reilly’s loyal audience of roughly 4 million viewers stick around without O’Reilly on the air? Will advertisers that abandoned O’Reilly return to back his replacement? Will the loss of the network’s most popular host set off a ripple effect that diminishes the rest of Fox’s lineup?

Fox’s dynastic Murdoch family — patriarch Rupert and sons James and Lachlan — cashiered O’Reilly after a nearly three-week drama surrounding sexual harassment allegations against him. O’Reilly and the Murdochs were unable to ride out the public-relations debacle triggered by accusations that he had abused female employees throughout much of his 21-year career at the network.

O’Reilly, the biggest star on cable TV news, will walk away from Fox with as much as $25 million, a severance figure set by the contract he signed only last month, a source close to the negotiations confirmed to The Post. He just last month reupped at the network with a three-year contract whose terms reportedly awarded him a year’s salary in severance.

Neither Fox nor O’Reilly’s representatives have officially disclosed what O’Reilly’s severance will be. The contract’s play-or-pay terms made his booting relatively simple, if financially painful, for the Murdochs.

(Peter Stevenson/The Washington Post)

For his part, the characteristically loquacious O’Reilly went relatively quietly. He issued a statement on Wednesday saying, in part, “It is tremendously disheartening that we part ways due to completely unfounded claims.” He hasn’t said anything further about his future.

O’Reilly’s summary dismissal may have lifted the immediate cloud over Fox. But it also raised new issues.

[Bill O’Reilly’s career comes to a swift end at Fox News]

Among the largest: Has Fox really reformed a workplace culture that saw the removal of its co-founder Roger Ailes last summer due to serial harassment allegations? Given that almost all of the senior executives hired by Ailes remain in place at Fox, that’s still an open question.

The programming issues seem more prosaic by comparison. Tucker Carlson, who will replace O’Reilly at 8 p.m., proved to be a strong successor to Megyn Kelly after she abandoned her 9 p.m. program and jumped to NBC in January (Carlson and Kelly, of course, benefited from the enormous lead-in audience O’Reilly supplied). Now, seemingly all at once, Carlson will be the linchpin of Fox’s lineup; he will precede Fox’s new 9 p.m. program, “The Five” (which formerly aired at 5 p.m.), followed by network fixture Sean Hannity at 10 p.m.

Fox has weathered this game of musical chairs before and come out even stronger in the end. Greta Van Susteren jumped ship last summer, landing at MSNBC, followed by Kelly’s departure. Result: Fox rolled on to record audiences during the next three months, perhaps aided by coverage of President Trump’s new administration.

But O’Reilly may be different. He has been Fox’s signature name for two decades, and unlike Kelly or Van Susteren, the “tentpole” propping up the rest of Fox’s schedule.

“The departure of O’Reilly is a big hit to FNC, but it is by no means fatal,” said Jeffrey McCall, a DePauw University professor who studies the news media, in an interview on Thursday. “For one thing, the [Fox] brand is bigger than O’Reilly, and further, the people who watch really have nowhere else to go for the kind of news they seek. CNN and MSNBC will not benefit from O’Reilly’s departure.”

He expects Fox’s ratings and image to recover, particularly since Carlson speaks to the same older conservative audience that was O’Reilly’s core viewer. The change may eventually even prove beneficial, he added: Carlson, 47, is 20 years younger than O’Reilly, and thus gives the Murdochs a younger face around which to build the network’s future.

Audience surveys on O’Reilly’s effect on Fox News are somewhat murky, notes Dan Cassino, a professor at Fairleigh Dickinson University and the author of “Fox News and American Politics.” It’s unclear, he said, whether viewers come to Fox News to watch O’Reilly and stick around to watch other programs, or vice versa.

Nevertheless, “my sense is that any replacement will likely get lower ratings initially,” he said. “But that could actually wind up being more profitable for the network, as a Tucker Carlson is a heck of a lot cheaper than Bill O’Reilly is, so marginally lower ad rates aren’t going to hurt as much as they otherwise would.”

Already, the sponsor boycott that seemed to seal O’Reilly’s fate is showing signs of receding. . Several sponsors — Mercedes-Benz, Hyundai, Mitsubishi, Sanofi Healthcare — said on Thursday that they are “reevaluating” their plans.

And one of the first companies to pull its ads from “The O’Reilly Factor” says it’s coming back. The men’s fashion company Untuckit said it has told Fox that it would like to restore its ads to the hour formerly occupied by O’Reilly.

“Our concern, and the reason we initially pulled our ads, pertained to the disturbing allegations made against Bill O’Reilly and not with Fox in general,” said Untuckit’s chief executive, Aaron Sanandres, in an interview. “Fox indicated their decision to terminate Bill O’Reilly’s contract was made after a thorough and careful review of the facts and so it appears it was a fully informed one. I fully respect Fox’s decision. Accordingly, we plan to return to the 8 p.m. hour and will continue to allocate a portion of our advertising dollars to Fox.”

If other advertisers follow suit, as is likely, the net effect of the sponsor exodus will have been both minimal and yet profound.

Minimal because Fox appears not to have lost any money when dozens of companies pulled their ads from O’Reilly’s show when the New York Times revealed in early April that Fox and O’Reilly had agreed to a series of secret settlements over his harassment allegations. The ads were simply rescheduled and appeared at other hours during Fox’s broadcasts.

But the boycott ultimately had a devastating effect on O’Reilly. According to people close to him, the Murdochs concluded that sponsors were unlikely to return to “The O’Reilly Factor” as long as there was a chance of new accusations. In the end, even though O’Reilly’s audience remained loyal, there was no assurance that sponsors would be.