Mr Aznar may now try to set up a rival front of parties in the Basque country, made up of his own conservative People's Party and the Socialists, who both want to keep Spain's existing constitution, with its strong measure of regional self-government but with no option for independence.

ECONOMIST: Spain and the Basques

Post-war Germany bound itself with rules and treaties in order to resist past temptations: a strong constitution to restrain politicians, fiscal rules to banish hyperinflation, the EU to tame nationalism.

ECONOMIST: Charlemagne

That is the way it was meant to be when the German constitution was written after the war, with the Americans having a strong hand on the pen.

BBC: Constitutional issues could stop Merkel buckling