If Bush really cared about the GOP, he would veto any immigration reform bill, i.e., amnesty or legalization of status. Besides being the right thing to do, this could be a winning issue for the Reps in 2008 as long as McCain isn't heading the ticket.
He isn't going to veto anything like that. This is what he has wanted for a long time. He had to be dragged kicking and screaming to the fence bill and only signed it because he knew it would never get built, that he could sign his scamnesty bill after the 2006 mid term elections. He could have done the right thing prior to the 2006 mid term elections and helped the republicans. He didn't, so why would he cave at this last hour when he finnaly can get what he wanted?