You're forgetting his promise to expedite the return of the so-called good illegals. Won't matter much if he deports 20 million if he figures out a way to expedite the return of 16 million of them. Just saying ...........
He never "promised". As he was ramping up public support he said we'll "try and bring the really good ones back on an expedited return". Later when pressed on it, he mentioned "doctors, well-educated ones" as an example. Then later pressed the point "remember there's other people who already want in who didn't violate our laws so that has to be considered". Then later pressed the point "they can't be harming us in anyway, taking jobs Americans want". Then boom the ban on Muslim immigration.

When you follow the strategy of how he's united this nation against illegal immigration and in support of mass deportations and done so with such few words, such little effort, but with a keen strategy it's remarkable really. And he'll remember every exact word he said, and every word is on video.

And he's not done. He'll be ramping it up again to a full moratorium on all immigration for a period of years.