“Gradually and then suddenly” is the story of Joe Biden’s physical and cognitive decline. “Gradually and then suddenly” is how his army of enablers in the media, the Democratic Party and the donor base abandoned his defense. “Gradually and then suddenly” is how he gifted his party and his country with a full-scale political crisis, centered on a president who no longer appears fit for office and whose vice president (and presumptive successor) is widely disliked. 

Years ago, Ronald Reagan wrote, elegiacally, that the sun was setting on his life. But by then, he was a former president, living in retirement on his ranch. He was not occupying the Oval Office, holding down the most powerful and demanding job on earth. 

Joe Biden is. The public no longer thinks he is fit to do that job. They reached that firm conclusion after watching the debate Thursday night and then hearing nothing from Biden’s allies to convince them otherwise.