Her most powerful message against Trump might be a non-ideological one: His lack of knowledge, seriousness and impulse control make him too dangerous to put in the presidency.

That strategy would have room for many specific criticisms of him that fit within the overall message of his unfitness. Instead of presenting his $11 trillion tax cut as a typical right-wing scheme, for example, she could tie it together with his speculation about defaulting on the debt and suggest that he is far more reckless than normal conservatives. (His encouragement of other countries to get nuclear weapons also illustrates this point.) And she would have to outsource some potential attacks to others. Calling Trump a “fascist,” for example, would make her rather than him look wild-eyed.

Clinton would be presenting herself as the candidate of safety. This strategy has its dangers, too. One is that people will decide, as Trump campaign manager Paul Manafort says, that he “can fill the chair.” Another is that Clinton would also become the candidate of the status quo at a time most Americans are dissatisfied with it. But this might be a risk worth taking. Henry Olsen, a conservative election analyst at the Ethics and Public Policy Center, says: “She needs to be the candidate for the person who is not irretrievably committed to blowing up the system. And I don’t think there’s a majority of those people.” The fact that the incumbent president has a 51 percent approval rating in the same Washington Post-ABC poll that has Trump slightly ahead suggests that Olsen is right.