I watched the Biden-Trump debate alone in a Lisbon hotel room, and it made me weep. I cannot remember a more heartbreaking moment in American presidential campaign politics in my lifetime, precisely because of what it revealed: Joe Biden, a good man and a good president, has no business running for re-election. And Donald Trump, a malicious man and a petty president, has learned nothing and forgotten nothing. He is the same fire hose of lies he always was, obsessed with his grievances — nowhere close to what it will take for America to lead in the 21st century.

The Biden family and political team must gather quickly and have the hardest of conversations with the president, a conversation of love and clarity and resolve. To give America the greatest shot possible of deterring the Trump threat in November, the president has to come forward and declare that he will not be running for re-election and is releasing all of his delegates for the Democratic National Convention.

The Republican Party, if its leaders had an ounce of integrity, would demand the same, but it won’t, because they don’t. That makes it all the more important that Democrats put the country’s interests first and announce that a public process will begin for different Democratic candidates to compete for the nomination — town halls, debates, meetings with donors, you name it. Yes, it could be chaotic and messy when the Democratic convention starts on Aug. 19 in Chicago, but I think the Trump threat is sufficiently grave that delegates could quickly rally around and nominate a consensus candidate.

If Vice President Kamala Harris wants to compete, she should. But voters deserve an open process in search of a Democratic presidential nominee who can unite not only the party but also the country, by offering something neither man on that Atlanta stage did on Thursday night: a compelling description of where the world is right now and a compelling vision for what America can and must do to keep leading it — morally, economically and diplomatically.

Because this is no ordinary hinge of history we are at. We are at the start of the biggest technological disruptions and the biggest climate disruption in human history. We are at the dawn of an artificial intelligence revolution that is going to change EVERYTHING FOR EVERYONE — how we work, how we learn, how we teach, how we trade, how we invent, how we collaborate, how we fight wars, how we commit crimes and how we fight crimes. Maybe I missed it, but I did not hear the phrase “artificial intelligence” mentioned by either man at the debate.

If there was ever a time that the world needed an America at its best, led by its best, it is now — for great dangers and opportunities are now upon us. A younger Biden could have been that leader, but time has finally caught up with him. And that was painfully and inescapably obvious on Thursday.

Biden has been a friend of mine since we traveled to Afghanistan and Pakistan together after Sept. 11, 2001, when he chaired the Senate Foreign Relations Committee, so I say all of the above with great sadness.

But if he caps his presidency now, by acknowledging that because of age he is not up to a second term, his first and only term will be remembered as among the better presidencies in our history. He saved us from a second Trump term, and for that alone he deserves the Presidential Medal of Freedom, but he also enacted important legislation crucial to confronting the climate and technology revolutions now upon us.

I had been ready to give Biden the benefit of the doubt up to now, because during the times I engaged with him one on one, I found him up to the job. He clearly is not any longer. His family and his staff had to have known that. They have been holed up at Camp David preparing for this momentous debate for days now. If that is the best performance they could summon from him, it’s time for him to keep the dignity he deserves and leave the stage at the end of this term.

If he does, everyday Americans will hail Joe Biden for doing what Donald Trump would never do: put the country before himself.

If he insists on running and he loses to Trump, Biden and his family — and his staff and party members who enabled him — will not be able to show their faces.

They deserve better. America needs better. The world needs better.