Mr. Sánchez and Mr. Torra met on Feb. 26 in a bid to renew negotiations and end a conflict that reached a boiling point in 2017, when Catalan separatists made a botched attempt to declare independence. When they met, Spain had just a handful of coronavirus infections, but the outbreak ballooned, pushing other business aside.

Separatists have governed Catalonia since 2015, but the conflict has split Catalan society down the middle, with the divide now influencing how Catalans view the response to the coronavirus.

At a checkpoint outside Igualada, Jordi Morente, an air-conditioner technician who has been stranded in the town, said that he wanted the whole of Catalonia sealed off. But his colleague, Toni Navarro, wanted Catalonia to stop trying to go its own way. “Now is not the time for politics, they have to listen,” Mr. Navarro said of the Catalan government.

Some health professionals on the front line of the emergency said such political bickering was not helping.

“We have to work all together, we cannot even afford losing a single minute with political fighting,” said Antoni Trilla, the dean of the University of Barcelona’s faculty of medicine, arguing that central authorities needed to lead the response. “The whole country is facing this threat.”

Elian Peltier reported from Barcelona, and Raphael Minder from Madrid. Megan Specia contributed reporting from London. Melissa Eddy contributed reporting from Berlin, Aurelien Breeden from Paris, Matina Stevis-Gridneff from Brussels, and Elisabetta Povoledo from Rome.