I haven't seen anyone seriously advocating mass roundups.
Welllll, you've been missing out on some fun! :-)
Me? I'm unhappy because I think it weakens President Bush yet again and thus weakens the war on islamofascism.
Here's the weird thing, principle(President Bush's views on immigration) wins out over politics. He simply can not draw a bright line between illegal and legal immigration and thus his principle, though wrong, remains steadfast.
A rarity indeed but the costs will be very expensive in my view.
"I haven't seen anyone seriously advocating mass roundups."
Mass roundups are NOT necessary! If their employers are sanctioned, they will get the hint. Most have too much invested in this country (cars, homes, etc) to see them lost due to unemployment. They will sell out and go back. Then return when they can do so legally.
This is not the final solution (that is 100% effective) but if we can reduce the presence to 10%, we are millions ahead.