Confusing Butterfly Ballot + Disenfranchisement of Thousands of Blacks that Aren't Felons = Bush wins
One might even go so far as to say that Bush 'won power', but that the process was not precisely an 'election' in the internationally accepted sense of a democratic one. His operatives manipulated the outcome effectively both before and after the 'election' day through, primarily, disenfranchisement as Harry points out.
Of course this is par for the course. In fact the course itself - the electoral college - is designed to favour right-wing candidates.