Exit polls from the regional elections in Catalonia show that pro-independence parties are winning a huge majority: up to 95 of the 135 seats in the regional assembly, according to analysis from the Financial Times. Worse, from Madrid’s point of view, the radical pro-independence forces are doing unexpectedly well. The next Catalan government will now be convinced that it has a mandate to hold a referendum on independence that Madrid says is illegal.In a worst case scenario, the provincial authorities will attempt a referendum that the national government tries to block. It will be interesting in such a case to see whether the police obey local authorities or listen to Madrid. At the moment, no one knows what comes next; there is zero trust between Barcelona and Madrid right now.Catalan nationalism has been around for a long time, and occasional flareups and disputes are part of the normal pattern of Spanish life. But this is different. With EU-mandated austerity programs and bank restructurings underway, Catalans resent more than ever what they say are exploitative tax policies by which the Spanish government takes money from Catalonia and spends it on poor regions.Madrid retorts that the problem is out of control spending in Catalonia; the region has come to Madrid seeking a €5 billion bailout and is €42 billion in debt. Catalans say that if they could keep their money at home and run their own affairs they could manage much better.Be all that as it may, it’s clear what is pushing Spain into its worst constitutional crisis since the death of Franco: the colossal failure of the European currency union. European policy makers foisted a currency they did not understand on a continent that wasn’t ready for it, and the result is what may be the single most expensive economic policy fiasco ever seen. With neo-Nazis on the march in Greece, the extreme right making gains in eastern Germany, European public opinion everywhere turning harsh and inward looking and now a looming secession crisis in Spain, it seems evident that the final bill for the euro won’t just involve money.Spain must now come to grips with an angry and increasingly ambitious Catalan national movement — even as the country attempts to calm foreign creditors and implement difficult economic reforms. It will be hard — it may be impossible — to get it all done. Failure will be much more consequential than anything that has happened or can happen in Greece; we are on the edge of our seats as we wait to see what comes next.