I don't really care what he does with the people here now, but the freaking border needs to be secure. I don't even care if we let in everybody that wants to come in, but they shouldn't be able to do it by simply walking across the border. It's not good for them and it's not good for us.
What does "secure" mean? If you ask me our borders are secure. We have more fences, border agents and money spent on border security than ever. Even if we built a double layer fence across both our borders, people could still get into the country. You can overstay a visa, you can arrive on a rickety boat, etc. Unless you have a totalitarian state, there is going to at least the possibility of illegal immigration.
If you just legalize some type of immigration system that makes sense for our economy, and then use things like e-verify, you can cut off the pathway for people to want to come here illegally. That would enable us to spend less on border security because they wouldn't be looking for people hoping to become busboys, they would just be looking for drug smugglers and such.