NEW YORK– Fox News Channel has thrived despite losing founding leader Roger Ailes and next generation star Megyn Kelly within the past nine months. Wednesday’s firing of defining personality Bill O’Reilly will be its toughest test yet.

Fox moved quickly to install a new lineup after announcing O’Reilly’s exit due to several harassment allegations by women, which he continues to deny. Outside pressure isn’t leaving with him; members of the National Organization for Women demonstrated outside Fox’s headquarters Thursday, saying the company’s workplace culture won’t really change unless management cleans house of other high-ranking executives who knew about the sexual harassment but didn’t do anything.

For most of Fox’s existence, O’Reilly had been the linchpin of its success as the most visible and most watched host. Fox’s viewership at 9 p.m. went up when Tucker Carlson replaced Kelly in January — her battles with Donald Trump cost her support among many Fox viewers — but don’t expect Carlson to repeat the feat when he moves an hour earlier on Monday.

“There’s going to be some dismay among the Fox audience,” said Tim Graham, director of media analysis at the conservative watchdog Media Research Center. “The real question is what happens next. If they offer the same generic product, then it will be forgive and forget.”

Announcing a new lineup at the same time as the O’Reilly firing was smart, Graham said, because it enabled some viewers to say, “Oh, that’s not bad. I can live with that.”

Fox News has consistently been the most-watched network in all of cable television, not just news, over the past few months. The ouster of Ailes due to sexual harassment allegations last summer may have been disturbing, but meant little to viewers because it was off the air. Most of his management team remained, and the network’s approach didn’t change.

O’Reilly’s brand of middle-class populism, delivered with a mix of humor and outrage, predated and reflected the appeal of President Donald Trump. O’Reilly wasn’t always predictable in his opinions. Joe Pollak of the right wing Breitbart.com web site wrote a column on Thursday headlined, “Bill O’Reilly’s secret: he was a centrist, not a conservative.”

Arguably, the lineup installed in his stead is more reliably conservative. Carlson has made it a point to seek a younger audience by reaching out to the alt-right community, said Angelo Carusone, president of the liberal Media Matters for America. Eric Bolling begins his own show at 5 p.m. and the current late-afternoon panel show, “The Five,” moves into the 9 p.m. hour.

“It’s not like they brought in Shep Smith or a news anchor,” Carusone said.

Carlson scored the highest ratings ever for Fox in the 9 p.m. time slot early for the first three months of 2017, but there remains some question about how much that was a result of following O’Reilly in the lineup. With him moving up an hour, 9 p.m. likely represents Fox’s biggest challenge. “The Five” is set up as a panel show with one liberal trying to hold his own with four conservatives. The panelists are familiar to Fox viewers, and O’Reilly protege Jesse Watters is being added to the mix.

“The Five” faces strong competition with MSNBC’s Rachel Maddow in that hour, and CNN is about to give Jake Tapper a test drive in the time slot.

Trump’s most ardent defender on Fox, Sean Hannity, remains at 10 p.m. ET.

Meanwhile on Thursday, a handful of media outlets reported that O’Reilly could be receiving a payout of up to $25 million for leaving Fox — less than the $40 million Ailes was paid when he exited last summer.

Fox had its largest audience on the renamed “The Factor” Wednesday night since O’Reilly left for what became a permanent vacation, with the Dana Perino-hosted show seen by 3.34 million people, the Nielsen company said Thursday.