On the campaign trail, Republican presidential nominee Donald Trump wore his message proudly. (Jae C. Hong/Associated Press)
Media Columnist

When Donald Trump takes the oath of office Friday, becoming the 45th president, two factors will have helped in a big — no, huge — way. He had one dominant message and one dominant messenger.

A new Pew Research study shows that Trump voters coalesced around a single primary news source: Fox News.

Hillary Clinton voters did the opposite. Some watched CNN and MSNBC or local TV news; others read the New York Times or listened to NPR. No news organization got more than 18 percent of the Clinton-voting total, while Fox had 40 percent of Trump voters. (Facebook was a major distribution source for voters of all stripes but doesn’t produce its own news.)

As for the message, The Washington Post’s Karen Tumulty reported Wednesday after a telling interview with Trump that he arrived at his campaign slogan way back in 2012, just after President Obama was reelected.

“Make America Great Again,” and the red caps that kept it stuck in our minds, may indeed have been a “racist dog whistle” (or code language) to some observers, including former president Bill Clinton, who said, “That message where ‘I’ll give you America great again’ is, if you’re a white Southerner, you know exactly what it means, don’t you?”

But it resonated powerfully.

“I think I’m somebody that understands marketing,” Trump told Tumulty in a rare moment of understatement. Indeed, Trump’s theme was memorable and constantly hammered home. Clinton’s was muddled and hard to understand.

In the final months of the campaign, Fox News was his willing partner. Granted, the network has some solid, independent journalists; it also has a sizable share of conservative shills and a right-leaning philosophy that was able to fit itself around the Trump agenda.

And especially following the Republican primary, Fox — invented two decades ago as an antidote to the mainstream media’s liberal leanings — seldom got off the script.

Now, Trump is rewarding Fox with interviews that solidify that alliance, and he’s largely staying away from those that challenged him.

“Look, I don’t think it’s any coincidence that friendly outlets have been the ones that have ended up with the interviews,” CNN President Jeff Zucker in a just-published interview with Gabriel Sherman of New York Magazine. Zucker named not only Fox News but also the Wall Street Journal and the Times of London — all within mogul Rupert Murdoch’s media galaxy.

That Fox is doubling down on its winning formula became even more apparent this month. The corporate brass chose the petulant partisan Tucker Carlson to replace Megyn Kelly — known for sometimes challenging Trump — in a coveted evening time slot following Bill O’Reilly.

It was Roger Ailes, a longtime Trump friend, who built Fox News from the ground up with Murdoch in the ’90s, becoming one of the most powerful media figures in the nation. The company clears well more than $1 billion in profit annually, and last year was a particular bonanza, with no end in sight.

Ailes was forced off his exalted perch last summer after credible claims of sexual harassment made him too toxic for the parent corporation, 21st Century Fox, now run by Murdoch’s sons. But given the election’s outcome, maybe 2016 wasn’t such a bad year for him after all, despite his stunning fall from grace.

One of the main tenets of news literacy — also known as being a well-informed citizen — is having multiple sources of news to compare, contrast and check against one another.

Clinton voters seemed to understand that, given their varied media diet. And of course, the outcome of the election is complicated, with the FBI’s unusual interference, likely Russian involvement, media stumbles and more in the mix.

But when it came to the all-important marketing war, it was simple enough: a red trucker hat, a slogan you could whistle to and a friendly media powerhouse got the job done.

Trump is already planning his 2020 reelection campaign, with a slogan at the ready: “Keep America Great!” And Fox News, pretty clearly, will have its megaphone handy.

For more by Margaret Sullivan visit wapo.st/sullivan.