But, in general, moderators need to avoid becoming part of the story. They should encourage direct interaction between the candidates, even if that means sitting back and missing out on the occasional follow-up question. Debates are not meant to be modified news conferences or interviews. The Annenberg report recommended cutting moderators out of the action as much as possible. With the particular challenges that Mr. Trump poses, of course, that may call for some adjustments.
The president has made clear that he will say anything, without regard to the truth. The debate hosts and moderators need to have multiple systems in place to deal with this and be willing to call him out. Real-time fact-checking resources should be beefed up, along with morning-after analyses. As an additional check, particularly egregious lies spread in one debate could be revisited in subsequent ones, with the candidates asked to respond.
The basic debate structure could use some tweaking as well. The common format of allowing each candidate 60 to 90 seconds to answer, followed by 30 seconds for rebuttals, is too rigid and provides insufficient time for thoughtful responses. It pushes participants to give every question equal time.
One proposed alternative is the chess clock model, in which each candidate would receive a total of 45 minutes, which would tick down whenever he or she spoke. Within reasonably broad parameters, a candidate could devote different amounts of time to different questions, for instance, spending twice as long on climate change as on decriminalizing border crossings — or vice versa.
Another Annenberg suggestion for helping candidates define their priorities: Give each contender two or three topics in advance, for which they would prepare meaty four-minute statements, and their opponent would prepare equivalent rebuttals. Topics could be determined variously by the candidates, the moderators and the voters.
Organizers really ought to consider losing the live audiences — even after crowding into a college auditorium is no longer a public health hazard. All the jeering and cheering encourages the candidates, and even some moderators, to play to the crowd. The crowd reaction, in turn, influences how the home audience processes the event. The entire set up lends itself to the kind of stunt Mr. Trump pulled at a 2016 debate with Hillary Clinton, to which he invited several women who had accused President Bill Clinton of sexual misconduct — and tried to seat them in his V.I.P. box next to the former president.
The presidential debates don’t have to be such circuses. The public and the candidates ought to demand better.