Bill O'Reilly

NEW YORK — With its biggest star departing in another blowup over sexual harassment, Fox News faces some big challenges. It now has to show that it can hang on to its loyal army of conservative viewers, improve its working culture, and still continue to make big bucks for its corporate parent.

The company said Wednesday that it had parted ways with longtime host Bill O’Reilly after a “thorough and careful review of allegations against him.” Dozens of advertisers ditched “The O’Reilly Factor” after a New York Times report detailed $13 million in payouts to five women over his alleged abusive behavior; more allegations subsequently emerged. (O’Reilly denied the accusations.)

O’Reilly’s departure is the second big blow for conservatives’ favorite news network in nine months. Fox’s longtime CEO Roger Ailes resigned abruptly amid similar sexual harassment charges last July. Its leading female star, Megyn Kelly, also decamped in January.

The network’s parent company, entertainment giant 21st Century Fox, insisted that Fox News will weather the storm, noting in a statement the “strength of its talent bench” and expressing “full confidence that the network will continue to be a powerhouse in cable news.”

That certainly could happen, though it probably won’t be easy.

Some analysts believe that James and Lachlan Murdoch — the sons of 21st Century Fox executive chairman Rupert Murdoch — made the call on O’Reilly to change the Ailesian culture at the network and to cement their control following his departure.

“Getting rid of the old guard is a way to do that,” said Dan Cassino, a professor at Fairleigh Dickinson University and the author of “Fox News & American Politics: How One Channel Shapes American Politics & Society.”

But O’Reilly has been on Fox News for more than two decades. “The O’Reilly Factor” has generated a huge ad bonanza for Fox, one that yielded more than $178 million in 2015. It’s the top-rated show on the No. 1 cable network — one that, according to the investment bank Nomura’s estimates, accounts for fully 20 percent of profits at 21st Century Fox.

Now, the top ratings for O’Reilly’s time slot — and Fox’s other prime-time shows — could be at risk. “He’s been the linchpin,” said Jane Hall, an American University professor and former Fox contributor, who noted that it will take a while to see whether his audience sticks with O’Reilly’s replacement.