I was actually pretty impressed with the immigration reform GW Bush tried to pass, but failed. Increase enforcement along with a process to legalize the ones already here. My memory is hazy on the details, but unless you've lived illegally in the US for more than X years (those people get legalized within the US), you need to leave the country, then apply and return. Of course this is dependent on having a good enough process to let them back in (which I remember it was), but it seemed a good compromise between enforcement and increased immigration.