NBC News anchor Lester Holt is currently preparing questions for the GOP and Democratic nominees at a time when the media and American voters are engaging in their own debate: over the role and obligations of a moderator. When it comes to televised debates that offer voters some of their final, close looks at the leading candidates for the nation’s highest office, should Holt act as a fact-checker who challenges anything he finds false or misleading coming from the candidates?

Or, is his job—and the job of past and future debate moderators—simply to referee the debate, making sure each candidate has space for a response or challenge?

Trump has already swung back and forth between praising Holt as “a professional” and suggesting that the debate process (and the entire election, for that matter) is “unfair.” At one point, Trump even claimed Holt is a Democrat, even though the anchor is a registered Republican.

Fox News anchor Chris Wallace, who will moderate another Trump-Clinton debate next month, is on the record as believing that it isn’t the job of a moderator to fact-check in the middle of a debate. “I do not believe it’s my job to be a truth squad,” Wallace said recently. While Wallace does have supporters in the media, many have also argued that he is wrong, and that journalists have a duty to spotlight the truth.

It’s an important issue for TV networks, as the upcoming debate is expected to be the most-watched presidential debate in history, with a potential to pull in more than 100 million viewers—a viewership level normally reserved for the Super Bowl. While the debate is commercial-free, networks are easily selling out ad space for their debate coverage before and after the 90-minute event.

AdWeek reported that some networks are expecting multi-million dollars in ad revenue for debate night.

Wherever you stand on the issue, it is clear that moderators’ performances have become part of an ongoing, frothy debate.