I think that the debate question where they asked if he would support the death penalty if someone raped and murdered his wife really hurt him. Instead of asking why someone would ask such a horrific question, he just droned on about how he opposed the death penalty.
He actually flip flopped on the death penality while answering that question. He said that he opposed the death penality, but was still very tough on crime.
Plus, Bush used negative advertising the whole campaign, while Dukakis tried to ignore it but failed. Then when he responded he came across as a whiner