1st and caustic answer: Only if the voting public in the Unites States had the same kind of spine as the voting public in Spain.
But I will be fair both ways: the Spanish were already very divided and it was the diversion of a very small number of votes that made the difference. We in the U.S. are nearly as equally divided and a "Spanish vote" (to coin a term) is a possibility. OTOH, I don't believe that given an atrocity here that so many of us would cave; if anything (caveat: I Am Not A Pundit) I think overall we would move in the opposite direction. As we did, briefly, post-9/11.
I truly believe that if Al-Qaeda attempts such an effort here that it will backfire on them.
I happen to agree. But I wanted to see your thought process.