Megyn Kelly, right, listens as Fox News colleague Chris Wallace begins introductions during the first Republican presidential debate on Aug. 6 in Cleveland. (John Minchillo/AP)

There was a moment in Tuesday’s Republican presidential debate when Donald Trump, as is his custom, complained about unfair lines of questioning.

In an interview with Trump less than 24 hours later, Fox News host Bill O’Reilly gave the GOP front-runner another chance to air his grievances with CNN, which broadcast and moderated the rhetorical showdown from Las Vegas.

But Trump didn’t want to gripe about CNN anymore. He wanted to knock Fox, instead.

O’REILLY: Do you think CNN dislikes you -- the news organization itself?

TRUMP: Well, honestly, I think I get better press from CNN than I do Fox, Bill, if you want to know the truth.

O’REILLY: Well, that’s because we’re the toughest network.

Laugh all you want, Fox haters, but O’Reilly might be right — at least as far as the 2016 Republican presidential primary goes.

You’d have to be in a Rumpelstiltskin-esque slumber not to know that Trump has been carping about Fox coverage for months now. The thing that really set him off was a debate question in August from Fox News host Megyn Kelly, who confronted him about his propensity for ad hominem attacks on women. That, of course, led Trump to remark the next day that Kelly had “blood coming out of her wherever” — a perfect confirmation of her question’s premise — and Trump has continued to blast Kelly and the network ever since.

Now, it’s certainly true that Trump has targeted seemingly every media outlet for ridicule, at some point. And making a candidate unhappy isn’t the same as covering him well.

But Fox has gotten under Trump’s skin more often than most, with tough questions and reasonable critiques on proposals like blocking all Muslims from entering the United States and building a wall along the Southern border to keep out Mexicans.

And it’s not just Trump getting a thorough vetting from Fox. Sen. Ted Cruz (Tex.) wilted in an interview on Wednesday when Bret Baier pointed out that Cruz’s recent statements about never supporting a path to legal status for undocumented immigrants is inconsistent with what he said two years ago.

After the Islamic State attacks on Paris last month, Chris Wallace grilled Ben Carson on foreign policy during a 10-minute interview that exposed — as well as any other — the retired neurosurgeon’s lack of command over an issue that has been widely attributed to his decline.

Meanwhile, Fox News and its sister, Fox Business, have also done the best job of using social media to give voice to Republican voters during primary debates.

Come general election season, Fox will almost certainly be accused of favoring the Republican nominee over the Democrat. And maybe that accusation will be warranted.

But during the primary season, Fox’s conservative reputation is an asset. It’s actually liberating, in a way. Fox News can charge hard at GOP candidates, and the scrutiny will make the network appear less biased than many people think. A more liberal competitor like MSNBC, however, risks looking more biased when it holds Republican White House hopefuls' feet to the fire.

Plus, Fox knows that Republican voters consider it to be more credible than other major news sources. In a Pew Research survey last year, 88 percent of respondents who described themselves as “consistently conservative” said they trusted Fox News. At a time when just 40 percent of the general public trusts the media overall, that’s a huge number.

Fox’s news and analysis carries tremendous weight with the conservative audience most interested in the Republican primary. And right now, the network is doing a pretty good job of throwing that weight around.