 Mr. Biden speaks frequently to his son, Hunter Biden, who calls and texts the president and first lady multiple times a day to see how they're coping with the onslaught of scrutiny surrounding his father's health, mental fitness, and final presidential campaign. Recent interviews with more than three dozen people, some of whom spoke on the condition of anonymity to discuss private conversations about the campaign, reveal a truth about the state of Mr. Biden's campaign. The people steering Mr. Biden through the biggest political crisis of his presidency are true believers in the mythology of Joe Biden as the comeback kid and discount opinions to the contrary.