Let 'em drop.
Also, GHWB lost in part due to breaking his own word on "no new taxes"; GWB, on the other hand, never made any promise not to grant amnesty to illegals. On the contrary, he gave plenty of clear signals what his true intentions were on this matter.
Finally, GWB does not need to fear another Perot, nor do the Dems appear to have any candidate waiting in the wings who is anywhere near as charismatic as W.J. Clinton (Hillary will melt like the proverbial Wicked Witch of the West, if exposed to a national electorate, IMO), and, also, GWB can ride the "war on terrorism" indefinitely, whereas GHWB ended the Gulf War far too quickly for any effect of it to least until the 1992 election. "Perpetual war for perpetual peace" means that the President can milk his war powers perpetually, rather than for limited duration.
I'm not saying that GWB won't suffer for his amnesty stance, I'm just saying he has more positives going for him than we give him credit for.