President Biden, 81 years old, was hoping to convince Americans that concerns about his age are greatly overstated. So far, his performance isn’t succeeding in making a great case. Biden sounds hoarse and at times was hard to understand—“Is Biden sick” was trending online—and he noticeably lost his train of thought while discussing inflation and healthcare. Later, after Biden made comments about the border, Trump retorted: "I really don't know what he said at the end of their sentence. I don't...