I personally think that it´s al-Qaida - or some organisation that has links to
it - that was behind the atrocity. ETA wouldn´t survive an attack like this;
it would lose it´s support. Still, even if it´s al-Qaida - which even the PP
probably acknowledges after the elections - ETA will find it very hard to
continue it´s attacks. ETA declaring ceasefire in whole of Spain wouldn´t be surprising, especially if the ruling conservatives lose the election.