An air of improvisation, of transience, has suffused José Luis Rodríguez Zapatero’s government in Spain since his unexpected general election victory four years ago in the aftermath of the Madrid train bombings.

That event, in which 191 people died (and for which 21 Islamist militants were last year convicted), has cast a long shadow over Spanish politics. The conservative Popular party never accepted its defeat, which it blamed on the terror attack. As a result, Spaniards hope the election on Sunday will end one of the most bitterly divisive periods since the restoration of democracy 30 years ago.