If you are of Hispanic origin and reside legally in the USA. Would you (a) want loads of "your" people coming across illegally and then getting rewarded with residency through an amnesty of some form, and of course this says nothing about the increased competition for resources (jobs etc.) (b) Feel threatened and prefer the status quo whereby you have elevated status via legal residency.
Trump is saying nothing all that different to the standard repub lines over the past 8 yrs I've lived here, but the difference is that he is from outside of the previous bunch of liars etc. The establishment repubs are in full on panic mode and it's an incredibly interesting thing to observe!
Trump will most likely beat Hillary too, happy Wednesday!