We’re not going to catch 100% of them....but what we realistically need to do is catch enough of them and enforce the laws that we have to the point where they stop wanting to come here illegally.
I heard a good analogy the other day:
Illegal immigration is like a highway where there are no cops and everyone is speeding. One side says, "We can't arrest every motorist on the highway.", but that is a red herring.. All we have to do is put some patrol cars on the highway and ticket some of the speeders and the rest will slow down.
Same thing with immigration:
After all that is implemented we can talk about increasing legal immigration and regularizing the illegals who don't self-deport.