To further extrapolate your point: what if the OK City bombing went off on November 3rd 1996? {instead of 4/19/1995}; and BillyJeff Clinton came out of the box and blamed the "Vast RightWing Conspiracy"?
I think the same result would happen here in the USA as Spain: Many non-voters would be pissed-off enough to show up and vote against who they perceived to be a slanderer