The Maine Senate race is far from the first time that an American political party has had to choose between character and power.In 2017, Alabama Republicans nominated a state supreme court judge named Roy Moore for U.S. Senate. A month before election day, The Washington Post published a report that when Moore was a 32-year-old assistant district attorney, he initiated sexual contact with a 14-year-old girl. Three other women alleged that Moore had also pursued them when they, too, were underage. Asked on Sean Hannity’s radio show whether he had ever dated underage girls, Moore replied, “Not generally, no.” Then...