We can say with greater confidence that the epidemic has disrupted Mr. Trump’s general-election strategy. He had planned to organize his campaign around two themes: a strong economy and a critique of the Democratic Party for allegedly embracing “socialism.” No doubt his campaign would have fashioned its own version of Ronald Reagan’s “Morning in America” advertisement with its famous concluding line, “Why would we ever want to return to where we were, less than four short years ago?” And it would have done its best to equate Joe Biden’s preferred policies with those of Bernie Sanders and the Squad.

In today’s radically transformed circumstances, neither of these themes is likely to work. The president will have to hope that by Election Day the economy will be in recovery from a historically sharp downturn—and that the people will give him credit for the improvement rather than holding him responsible for the decline. Although this is possible, it is hard to find a precedent—not to mention that few economists expect a classic “V-shaped” recovery.

As for socialism: No Senate Republican voted against the $2.2 trillion Phase 3 rescue bill, an unprecedented expansion of government’s cost and reach. As it turns out, there are few libertarians in economic foxholes. M r. Trump has invoked the measures of war socialism, forcing General Motors and 3M under the Defense Production Act to accelerate plans to convert their assembly lines to health-equipment production.