The Original Sin co-author discusses the former president’s decline and why it still matters amid Trump’s chaos.

When CNN’s Jake Tapper went on his book tour, he probably did not expect it to turn into an apology tour instead. Yet that is what has happened as his media blitz has quickly given way to mea culpas.

A new book, detailing the inner workings of the Biden White House and campaign as it defended his mental acuity, labeled ...