For George Stephanopoulos, 22 Minutes of Probing the Personal.

It was, in the end, an interview as personal as it was political, a cross-examination more focused on the psyche and the inescapable reality of aging than on any points of policy or governance.

Respectfully but firmly, the ABC anchor George Stephanopoulos on Friday pressed President Biden, again and again, on the basic questions that Americans had asked themselves over the past eight days, since 51 million people saw a diminished Mr. Biden struggle to perform on the debate stage.

“Are you more frail?”

“Have there been more lapses?”

“Have you had a neurologist, a specialist, do an examination?”

And as Mr. Biden dismissed all those concerns one by one — flicking away the cascading worries about his health, his electability, his capacity to serve in his office for four additional years — Mr. Stephanopoulos zeroed in on the matters of pride, dignity and self-worth swirling beneath the surface.

“Are you sure,” the anchor asked, “you’re being honest with yourself?”

At 81, Mr. Biden is 18 years older than his interlocutor. The president arrived at the ABC interview on Friday tanned and tieless, his top two shirt buttons undone, making every effort to project youth and vitality. Yet a viewer could not help but imagine the mop-haired Mr. Stephanopoulos in the role of an adult son, guiding an elderly parent toward a conclusion that may be difficult, and deeply painful, to accept.

It is too soon to say if their 22-minute encounter on Friday, taped in the library of a Wisconsin middle school and broadcast by ABC in prime time, will count among the most consequential interviews in presidential history. But it carried some of the highest stakes.

Democrats’ confidence in Mr. Biden’s ability to defeat his Republican opponent, former President Donald J. Trump, plummeted in the aftermath of last week’s debate. The president’s soft voice, extended pauses and slurred words — once viewed by supporters as an unsettling, if benign, fact of his public appearances — had taken on far darker implications.

Mr. Biden evinced many of those traits again on Friday, his voice turning hoarse and hesitant at times. His answers occasionally meandered. He was much improved from the shaky president who stood across from Mr. Trump last Thursday, but neither was he in the fighting form of his 2020 debates.

When Mr. Stephanopoulos jumped straight to the point — “You and your team have said you had a bad night” — Mr. Biden bared his teeth in a smile.

“Sure did,” he replied, equal parts humility and nonchalance. Hey. It happens.

But then the anchor began to press. Nancy Pelosi, the former House speaker and an ally of the president, wondered if Mr. Biden had more serious health issues. Mr. Biden blamed jet lag, but he had been back from Europe for more than a week. Did he realize, onstage, how badly he was doing?

The president, who has interacted with Mr. Stephanopoulos for decades, including when the anchor served in the Clinton White House, tried to parry with some humor. “You’ve had some bad interviews once in a while,” he teased.

“I’ve had plenty,” Mr. Stephanopoulos replied. But, he pointed out, millions of people watched a debate that seemed to confirm fears about the president’s age.

When Mr. Biden blamed the press for amplifying the concerns of Democratic leaders, the anchor said he had heard from dozens of supporters who “want you to go with grace.” And when Mr. Biden tried to deflect by ticking off achievements of his administration, Mr. Stephanopoulos countered, “What has all that work over the last three and a half years cost you physically, mentally, emotionally?”

As the interview neared its end, Mr. Stephanopoulos pivoted back to realpolitik. “If you stay in, and Trump is elected, and everything you’re warning about comes to pass,” he asked, “how will you feel in January?”

“I’ll feel as long as I gave it my all and I did the good as job as I know I can do, that’s what this is about,” Mr. Biden said. (The original ABC transcript rendered the quote as “I’ll feel as long as I gave it my all and I did the goodest job as I know I can do, that’s what this is about.”)

At one point, Mr. Stephanopoulos posed a series of scenarios to Mr. Biden, about how he would react if top Democratic leaders called on him to withdraw. The president smiled and laughed.

“I mean, these hypotheticals, George,” he began.

The anchor interjected.

“It’s not that hypothetical anymore.”

The Times revised Mr. Biden’s quote in this article about how he would feel if he loses the election after White House officials and several news organizations contacted ABC on Friday about whether Mr. Biden had said “goodest” or “good as.” ABC’s standards team listened again to the audio and made the change. Mr. Biden’s actual words at that point in the interview were difficult to make out and open to interpretation.