With terrorist attacks, it is not uncommon for voters, perhaps feeling vulnerable, to rally behind the ruling government and avoid significant change. For example, after 9/11, public approval for President Bush in the United States rose dramatically. This did not happen in Spain.

XREF: Connects to political science literature on the rally-round-the-flag effect, most famously studied following the 9/11 attacks.

Green, Todd H, The Fear of Islam_ An Intro…, loc. 392