The quality of our leadership might not matter much in the initial “headless chicken” phase of a crisis when no one knows what they are doing, and many of the efforts will turn out to be useless or counterproductive. But, over time, luck matters less and management matters more. We expect leadership to get better, to learn what works and what does not, to understand the risks and progressively fine-tune their response. That is what European nations have done, and it is precisely what Trump has not. Months in, the president is still playing down the threat, still encouraging people to go out and gather in large groups, still hostile toward the wearing of masks.

The effects are evident in the stark divergence between the number of new U.S. and European Union cases. Graphs tracking the outbreak show the E.U. leading the United States until April, then the E.U. curve falls off sharply — from more than 30,000 cases a day to 4,000. The United States hits roughly the same peak a little later, but our curve enters a shallow glide, almost brushes 20,000 cases, then turns northward again. As of this writing, almost 35,000 new cases a day are emerging.

Not all of that can be laid at Trump’s feet. American federalism means local officials have considerable discretion over public health efforts. And the worst U.S. outbreak occurred under two Democrats — New York Gov. Andrew M. Cuomo and New York City Mayor Bill de Blasio — who initially rivaled Trump in their “see no evil” approach to covid-19. But the outbreak has shifted its locus to many states with Republican governors.