“We’re surrounded by so much false information and aggressive misinformation,” said James Goldston, the president of ABC News, who will oversee coverage from a Times Square studio built for the occasion. “The pain of getting it wrong in this environment would be very long-lasting.”

In interviews, network executives said that credibility was their first concern, and that they hoped to tune out competing chatter and focus on what they can control: getting it right.

“We’re editors, in a way,” said Mr. Stephanopoulos, as he sped up Madison Avenue in a yellow taxi after rehearsing on Sunday. “People are going to be coming to us, but they’re also going to be following this on their phones all day and getting all kinds of information. Part of our job is to sort through that and only give out what we can be sure of, in any given moment.”

To ensure independence, network statisticians are typically quarantined in an undisclosed location; some have their smartphones taken away. And despite the competitive pressures, network executives say they are willing to be patient.

“There’s no question that there’s added scrutiny this year of the entire system,” said Steve Capus, executive editor of CBS News. “If anything, I think that means we’re going to take our time to get it right.”