Bill O'Reilly returned to Fox News to air his grievances and regrets with Sean Hannity

Ousted Fox News host Bill O'Reilly defiantly returned to the network for the first time since he left earlier this year amid sexual-harassment revelations, saying he should have fought harder to stay.

In a lengthy conversation with host Sean Hannity on Tuesday, the two hosts discussed at length their opinions on the news of the day, criticizing the media and NFL players protesting police brutality and racial injustice by kneeling during the national anthem. 

Though the two largely avoided the subject of O'Reilly's departure, the former host lamented the advertising boycott that helped push him out.

"You fought back when they came after you last spring," O'Reilly said to Hannity, who fended off a similar advertiser boycott. "I didn't, and I should have."

O'Reilly also singled out Media Matters, one of the left-leaning watchdog groups that pressured advertisers to abandon both programs earlier this year.

"Did you know they threatened you and me if we did this segment tonight?" O'Reilly said of Media Matters, which monitors and publishes transcripts and clips of right-wing media. "These totalitarians want to wipe out any speech with which they disagree."

O'Reilly was far more muted than he has been in previous interviews about his departure from Fox News.

In an interview on Hannity's radio show earlier this month, O'Reilly said he was focusing his efforts on a potential legal battle and investigation to clear his name, referring to some claims of sexual harassment against him as a "kind of defamation," though he hasn't offered many specifics.

"What we're going to uncover is shocking," O'Reilly said.

O'Reilly has reemerged after several months of largely avoiding the spotlight, apart from prescheduled appearances and social-media images of his dog.

In promoting his new book, the former host has sat for interviews with Breitbart News, The Hollywood Reporter, and NBC's "Today" show, where he clashed with host Matt Lauer, who pushed back on O'Reilly's claim that the revelations of sexual-harassment allegations against him were a "hit job."

Despite reports that some employees at Fox News are not happy with the ousted host's informal return to the network, Tuesday's interview likely won't be O'Reilly's last on Fox.

Asked by Hannity whether he'd return to the show, O'Reilly said he needed to sell his book.

"I'll come back," he added.