I am reminded of the story about Reagan. When asked for his Cold War strategy, Reagan said: "We win". That sort of resolution was the key. It was more important than the nuts and bolts of any strategy.
Illegal immigration is either a problem, or it's not. If it is a problem, then the strategy is: "We end it". Only Trump seems to approach problems this way.
"Do you believe illegal immigration is a problem or not?"
They could say no and equivocate but if they say yes, then Trump is in control of finding solutions.