The mythology of the presidential debate — as a kind of civic single combat, mano a mano, with the nation’s future at stake — has its origins in the fall of 1960, when John F. Kennedy and Richard M. Nixon faced off four times on live television. Decades later, the New Yorker writer and editor Roger Angell still could summon the feeling of “common pride and excitement,” the sense that the country had witnessed “something complex, historic and profoundly American.”

The enterprise, since then, has gone sour and flat, like so much else in our political life. CNN, which will host the first of two debates between President Biden and Donald Trump, is doing its best to gin up the old excitement, but the general feeling is one of unease. Shelby Grad, a Los Angeles Times editor, asks whether the debate is “the ultimate hate watch.” Matthew Continetti of the American Enterprise Institute, speaking for many, says he will watch “in a fetal position.”

But the problem, really, is not the debates. It’s the debaters — and this whole wretched rematch of a campaign. Time labels it “the dread election.” Across a wide range of backgrounds and beliefs, Americans describe themselves in similar terms: exhausted, indifferent, depressed. A recently categorized voter, the “double hater,” is the star of a report that identifies Mr. Biden and Mr. Trump as the most disliked pair of presidential candidates in at least 36 years — twice as disliked, in fact, as they were in 2020. Watching them jab at each other for 90 minutes is unlikely to make them more appealing.

Why bother, then? In an election this close, if the debates make even a small difference, they could make all the difference. This is why Mr. Biden pressed so hard for an early debate. There is a way for him to win it, and decisively, but he will have to override his instincts, defy the constraints and conventions of presidential debates and tell a more compelling story — with clarity and force — about America’s future if Mr. Trump returns to power.

Mr. Trump, for his part, likes his chances. He believes, despite clear and convincing evidence, that he is pretty good at debating. “I think I won every debate” in 2016, he said this month. At the very least, he can be confident that just about any misstep will be drowned out or denied by his apologists. Still, Mr. Trump — who cannot be pleased with polls that show, in the wake of his felony convictions, some attrition among independent voters — appears to be aiming for a knockout blow.

Mr. Trump will be unalterably himself: nasty, relentless, brazenly dishonest. The real variable is his opponent, who forever seems one stumble away from oblivion. But the risk is worth taking; clearly, the Biden team feels that something must be done to shake things up. According to Gallup, Mr. Biden’s approval rating flatlined about a year into his tenure, and nothing has moved head-to-head polling averages more than a point or two — not a vigorous State of the Union address, not a strong economy, not Mr. Trump’s convictions on 34 counts. Apart from August’s Democratic convention, which will be as devoid of drama as the party can manage, the debates are Mr. Biden’s best opportunity to command a national audience before November.