Once again, to lay the blame on GWB any more than on ANY other congress or Prez for the last 40 years is unreasonable.
It was Bush who brought the subject to the forefront, not anyone else. Do I agree with his plan 100% - nope. Do I believe his plan is better than anything the demonrats are capable of coming up with - hell yes. Am I writing my congresscritters to back the House version- yep. Will the final bill be a combination of the house and senate bills- most likely.
And there is no reason to abandon the GOP, because the results would be far worse.
Ever heard of someone called Tom Tancredo ? Bush has always floated guest worker/amnesty plans that would have meant importing a third world serf underclass purely for the selfish interests of his buddies and to depress American wages.