Well there is another aspect to it. It is more than a rivalry. Liberalism has become their religion of sorts. They personally identify with liberalism and hate everyone "on the other side". It's quite simple and shallow. They no more hate Bush than they hate Delay or hate Rush. They only "hate" them if you want to call it that because Bush, Delay, Rush, etc are quarterbacks and running backs for the rival team they despise.
Go over and read DU for awhile. Its definitely hatred for Bush.
Islam=the religion of death
Liberalism=the religion of hate