Among the many complicated factors that have neutered Democratic power in this country—the alienation of young men, the rightward drift of certain minority voters, the MAGAfication of the Big Tech class, etcetera—one is relatively quite simple: age. It was Joe Biden’s age that doomed his presidential campaign and arguably dragged down Kamala’s; it was R.B.G.’s death under a Republican president that created the conservative supermajority on the Supreme Court. The death of three House Democratic incumbents in office this year dramatically reduced the party’s leverage over the majority, temporarily expanding Republicans’ tiny margin.