William F. B. O'Reilly Portrait of Newsday/amNY columnist Bill O'Reilly (March 28,

William F. B. O'Reilly is a consultant to Republicans.

A beloved cousin, L. Brent Bozell III, founded the Media Research Center in 1987. Its work exposing liberal media bias in mainstream American news coverage has been enormously influential.

Talk of news bias is axiomatic today because of Brent’s doggedness and insights. Here’s how publisher Steve Forbes put it: “Before the emergence of talk-radio, before Fox News, before online center-right alternative media, there was Brent Bozell. He pioneered an entire cottage industry that effectively holds the national media accountable before the public.”

His younger, less accomplished cousin made it a strict rule years ago rarely to speak of media bias when encountering it. When Brent was founding the MRC in Virginia, yours truly was embarking on a modest career as a press liaison in mostly New York Republican politics. (There is a such a thing.) It would be professionally counterproductive in the extreme to rip members of the news media whose objectivity I question, other than privately with them when necessary. It’s my job to interact with political reporters on a daily basis whether I think they’re fair or not. Most are. Many aren’t. One lives with it.

The most noticeably left-leaning reporters, in my experience, genuinely don’t see their bias. Their worldview is implicit in their writing, and more important in the stories they pursue and questions they ask.

I drove my wife’s car the other day. The tuner was set to NPR. This is the first question I heard in an interview: “What should Americans be most concerned about with the confirmation of Jeff Sessions as attorney general?”

President Donald Trump’s assaults on the news media are catnip to Americans who’ve been attune to and frustrated by decades of exchanges like that. It helps explain the cathartic joy some reported feeling in watching Trump’s biting news conference on Thursday. But such rejoicing obscures a new and greater danger to Americans who value anything roughly resembling objective reporting.

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When a president of the United States dismisses as “fake” news stories that challenge him, we have a problem far greater than any media bias. One may not like the way The New York Times or The Wall Street Journal cover a given news story — two outlets Trump singled out Thursday — but both publications have well-established reputations for fact checking and accuracy. Neither publishes “fake news,” and it’s dangerous to say so.

It’s also calculated. The so-called “alt-right,” with the aid of this president, is embarked on a treacherous venture made possible by years of legitimate objection to liberal news bias in national political reporting. It’s succeeding — not only in discrediting mainstream media outlets in the minds of millions but also in offering as equivalents unvetted propaganda outlets that are anything but.

One prolific alt-right outfit, Liftable Media, has unleashed several dubious nationalistic “news” sites like “Conservative Tribune” and “Western Journalism” that boast of being “Top 100 Ranked” media outlets.” I believe it: They flood social media feeds with timely, well-written agit-prop whose short-term goal appears to be delegitimizing anything anti-Trump and rationalizing the president’s persistently erratic behavior. Even less savory “publications” disseminate demonstrable untruths.

Within minutes of last week’s New York Times report about Trump campaign aides communicating with Russian intelligence officers, the alt-right network was out in full force, in striking symphony, driving a conspiracy narrative about Barack Obama-appointed intelligence officers. It worked. The unvetted narrative was competing with the actual news within an hour.

It’s becoming harder and harder to know which outlets and what information to trust. Talented propagandists from the political left and right have declared open season on the hearts and minds of unsuspecting Americans. They now have the mechanisms to win them. Such is a pitfall of this digital age in which a blog fired up yesterday can compete with a century-old news magazine.

The biases MRC has been bravely battling for 30 years may soon seem quaint. Who can police the emerging onslaught?

Williamm F. B. O’Reilly is a consultant to Republicans.