The moderators of this year's presidential debates could be in for a very rough ride.

Matt Lauer got a taste of what's to come on Wednesday when he moderated NBC News's "Commander-in-Chief Forum," where Donald Trump Donald John TrumpBubba Wallace to be driver of Michael Jordan, Denny Hamlin NASCAR team Graham: GOP will confirm Trump's Supreme Court nominee before the election Southwest Airlines, unions call for six-month extension of government aid MORE and Hillary Clinton Hillary Diane Rodham ClintonJoe Biden looks to expand election battleground into Trump country Biden leads Trump by 12 points among Catholic voters: poll The Hill's Campaign Report: Biden goes on offense MORE were interviewed separately.

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The long-serving "Today" show host came under a storm of criticism for his performance. He was assailed on social media, in major media outlets such as The New York Times and even by the campaign of Clinton, which sent out a fundraising appeal pegged to Lauer's purportedly unfair handling of the event.

The element of Lauer's moderation that sparked the most criticism was his refusal to push back on Trump's assertion that he was "totally against the war in Iraq."

Trump expressed support for the invasion in a 2002 interview with Howard Stern.

More broadly, the furor seemed like a warm-up act for the presidential debates beginning later this month. The first clash is set for Sept. 26. Lauer's colleague, "NBC Nightly News" host Lester Holt, will moderate.

The second debate, scheduled for Oct. 9, will be co-moderated by Martha Raddatz of ABC News and Anderson Cooper of CNN. Fox News's Chris Wallace will be in the chair for the final encounter, on Oct. 19. Elaine Quijano of CBS News will moderate the vice-presidential debate on Oct. 4, while C-SPAN political editor Steve Scully will be the back-up moderator for all four encounters.

The moderators of the presidential clashes will face a pairing unlike any other.

Center stage will be two nominees with historically high unfavorable ratings whose basic honesty is doubted by large swaths of the electorate. Trump has made it a habit to get combative with debate moderators, most notably Fox News's Megyn Kelly, while Clinton has her own history of tense relationships with the news media.

Meanwhile, online armies for both candidates will be ready to pounce on any instance — real or imagined — of moderator bias. And the campaigns themselves will be spinning furiously, eager to wring any advantage possible from "working the refs."

It's a scenario that makes even seasoned veterans uncertain of what is to come.

Bob Schieffer, who moderated presidential debates in 2004, 2008 and 2012, told The Hill, "We've never had an election quite like this, where you have two candidates and polls that show a large segment of the population doesn't trust either of them."

Schieffer, who retired from his role as anchor of "Face the Nation" last year but is still a CBS News contributor, added, "This whole thing is different. Trump is unlike any other candidate. ... [As a moderator] the idea is not to get into an argument with either candidate. But you have to be prepared."

The question of how much a moderator should inject himself or herself into the debate is more vexing than armchair critics acknowledge.

Lauer took flak from other well-known journalists, including The New York Times's Paul Krugman, for refusing to push back on Trump's Iraq War claim.

But back in 2012, CNN's Candy Crowley received considerable criticism, especially from conservatives, for going in the opposite direction: She interjected to suggest GOP nominee Mitt Romney had mischaracterized President Obama's response to the terrorist attack in Benghazi, Libya. Some thought Crowley was dead right or dead wrong; others argued that she had over-simplified an issue that had several shades of gray.

Ann Compton, then of ABC News, was one of a panel of journalists who participated in presidential debates in 1988 and 1992. Referring to the furor that followed Crowley's correcting of Romney in 2012, she told The Hill:

"There are still many people who think she was wrong and Romney was right. But while journalists are not there to be the police, they are there to defend facts. ... A journalist who does not follow up — and is not prepared to follow up with specific factual corrections — is in my opinion deserting part of the job."

Schieffer, however, held that it is better if moderators can leave room for the opposing candidate to tussle over facts rather than doing so themselves — at least right off the bat.

"If somebody says something and it is dead wrong, you have to first give one guy a chance to correct the other guy. The first fact-checker has to be the other candidate. If there's a fact that is egregiously wrong, then it is the moderator's place to correct that. But I think people want to know if the other guy knows it's wrong."

Schieffer — who was talking in general terms, not referring to the Crowley controversy — added that he believed audiences had limited patience for anything that could be perceived as showboating by moderators.

"People go to the baseball game to see the players," he said. "They don't come to watch the umpire."

The problem, some observers argue, is that this year's unusual campaign has had the effect of making some journalists into "players," whether they sought that role or not.

Trump's clashes with Kelly had the effect of making her part of the story, rather than a mere observer of it. The GOP nominee has also assailed various other journalists in harsh terms, from conservative radio host Hugh Hewitt to NBC News campaign-trail reporter Katy Tur.

"Any moderator is going to have a huge problem because of all of the scrutiny and attention that is going to be placed on this," said Grant Reeher, a professor of political science at Syracuse University. "I think these debates may be the most widely watched debates of all-time in our country. Given that likely fact, the person who is in the middle is going to be under a tremendous amount of scrutiny and pressure."

Wallace, who will moderate the third presidential debate, drew some criticism on social media when he told his network's Howard Kurtz over the weekend, "I do not believe that it's my job to be a truth squad."

But some experts, such as Reeher, are sympathetic to Wallace's position.

"The social media commentators have been expecting [moderators] to catch these things right in the moment when they think a candidate isn't speaking factually. I don't see that as the moderator's job," he said.

Such an approach, he added, "inserts the moderator as the third player in the mix, in a way. And, as a moderator, it's impossible to preserve your own impartiality then, because you have to make a decision as to when you insert yourself, how hard to push it, and things like that."

But others who have been under the presidential debate klieg lights argued that fact-checking is an essential part of the job — even if it inevitably will draw criticism.

"Asking questions of the potential future leaders of the free world is an art, it is not a science," Compton said. "The candidate cannot be allowed to thwart those questions with maneuvers that are either intended to make the reporter look like a bad guy or to shift the subject to something else."