Later, because nearly all states must balance their budgets, they couldn’t use deficit spending for bailouts. They can’t print money as the Federal Reserve can. And they still don’t have the resources to protect their residents — which makes it risky for them to anger Mr. Trump as they seek to fulfill their institutional role as a check against federal abuses.

Federalism’s limits have been apparent since the first reports of the virus emerged from Wuhan, China. In January, U.S. intelligence agencies warned that the Chinese government was minimizing the outbreak, but state and local officials didn’t have that information and so could not counter the president when he waved off the threat. In February, when the Centers for Disease Control and Prevention pledged but failed to put in place a system of widespread testing, states and counties didn’t have the capacity to act on their own. They had neither the centralized apparatus to conduct blanket testing nor the authority to waive regulations over such testing enforced by the Food and Drug Administration, another source of federal power.

The next task was undertaking the vast production and allocation of masks, other protective gear and ventilators. Instead of centralizing this task, President Trump said from the White House lectern, “Governors are supposed to be doing a lot of this work.” He added, “You know, we’re not a shipping clerk.”

But governors can’t invoke the Defense Production Act, which allows the federal government to order businesses to manufacture necessary medical equipment. Nor can they enlist the Federal Emergency Management Agency to manage the giant project of distributing the equipment. The vacuum left by the federal government forced states to compete for scarce equipment like ventilators, driving up their price and benefiting shady middlemen while causing fatal delays.

Mr. Trump has, characteristically, revealed and exploited defects in the federal system. Unwilling to take the blame for shutting down the economy when he thought there was little public support for the move, he sparred with governors like Mr. Cuomo and Gretchen Whitmer of Michigan while also hiding behind them.