Public TV’s Jim Lehrer, a veteran presidential debate moderator who handled last year’s first clash between President Obama and Republican Mitt Romney, said moderator fact-checking like Candy Crowley’s abrupt rebuke of Romney in the second debate is a fatal error that ruins the historic events–and should always be avoided.

“As a general premise, I believe debate moderators are not there as fact-checkers,” said Lehrer, host of NewsHour on PBS. “They are there to facilitate the exchange between the candidates. If there is going to be any fact-checking done, it should be done by the other person.”