Perhaps it would be less confusing for you if you considered that your so called 'bush haters', though 'they' generally disagree with the president on the subject of immigration policy, 'they' are actually many different posters.
And different people have different perspectives & opinions.
Or would that unduly complicate your view on the situation?
To the Bush ideologues, if you don't agree with the President 100% of time on 100% of his decision, youre a racist, xenophobic Bush hater.