Opinion | A Secessionist Crisis in Spain

The democracy Spain regained in 1978 faces a critical moment. The party of Pedro Sánchez, acting prime minister since July, is trying to make his role official by offering concessions to secessionists, unleashing a constitutional crisis.

July’s national elections threw Spain into upheaval, with the major parties all falling short of governing either on their own or through a likely coalition. That elevated regional parties into key blocs that Mr. Sánchez’s Spanish Socialist Workers’ Party has a history of courting. For the past five years, the Socialists have ruled the country in a coalition with Podemos, a populist extreme left-wing force. Among the Socialists’ supporters in Parliament is the Bildu party, political heirs of the terrorist group ETA.