If President Bush continues down this road, the coalition of people who will oppose him is already organized. There will be no delay as people who support him on the War on Terror decide whether or not to come out against him on amnesty.
He spent that goodwill, and got nothing for it. But just because he got nothing for it does not mean it was not spent. If he so much as breathes a word about amnesty between now and January 2009, the base will be all over him, and it won't be pretty.