There should be no illusions. Patrolling the border costs a ridiculous amount of money. It's one thing for a government to say, "OK, you can do this thing." It's another thing for a government to say, "OK, we will cough up the money to do this thing for you."
I don't think anyone is opposed, in principle, to enforcing the rules we have about who we let into the country. The trouble is simply that people disagree as to how much money should be spent on it. How much is enough? A thousand dollars, a million, a billion? So you build your multi-million dollar fence around Texas, and man it with dick cheney with his shotgun and a hundred cops (each who gets paid $40/yr), and then what? When the Latinos keep coming, just in boats instead of cars, will you fill the San Diego bay with water mines? Will you check every container in every truck and ship coming into the US from MX?
You could spend a trillian dollars, and still the Latinos would find a way in, as surely as we could find a way out. This is a fight to the death; and they will do anything to live.
The question is: how much money do we want to spend?