Don't you think he would veto a bill similar to HR4437? He has said all along for the past 7 years he's for a guestworker policy and being a man of his word, he hasn't budged an inch. I can't see that he would be willing to sign any real reform (assuming the idiots in the Senate would pass such a thing.)
The ironic thing is that most people (including me) wouldn't be against a guest worker program. The problem is that the current situation has to be rectified first.
If Bush would just enforce existing laws and stop the daily influx of thousands of illegals then most would give his guest worker program a shot.