There will be no opening statements. President Biden and former President Donald J. Trump will each have two minutes to answer questions — followed by one-minute rebuttals and responses to the rebuttals. Red lights visible to the candidates will flash when they have five seconds left, and turn solid red when time has expired. And each man’s microphone will be muted when it is not his turn to speak.

The candidates will get a breather during two commercial breaks, according to debate rules provided by CNN to the campaigns and reviewed by The New York Times, but they will be barred from huddling with advisers while off the air.

The first presidential debate of the 2024 cycle is less than two weeks away, and both campaigns are racing to prepare for the first showdown sponsored directly by a television network in more than a generation. The 90-minute contest in Atlanta on June 27 is circled as one of the most consequential moments on this year’s campaign calendar, as Mr. Biden and Mr. Trump will outline their sharply contrasting visions for the nation, appearing together for the first time since their last debate, in October 2020.

The two men are readying themselves for the debate in ways almost as different as their approaches to the presidency itself. The Biden operation is blocking off much of the final week before the debate, after he returns from Europe and a California fund-raising swing, for structured preparations. Mr. Trump has long preferred looser conversations, batting around themes, ideas and one-liners more informally among advisers. He held one session at the Republican National Committee headquarters this past week.

Mr. Trump and Mr. Biden plainly do not like each other. The former president calls the current president the worst in American history. The current president calls his predecessor a wannabe dictator who threatens democracy itself. Four years ago, in their first encounter, Mr. Trump trampled over his rival’s talking time — the former president has since admitted privately that he was too aggressive — with Mr. Biden scolding him, “Will you shut up, man?”

The rules circulated by CNN warn that this time, “moderators will use all tools at their disposal to enforce timing and ensure a civilized discussion.”