The GOP should go read that part of the legal stuff that says "conditions precedent". Maybe, even that bit on the college curricula that says "prerequisite".
NOT a guarantee. But a fact which MUST occur before green, ivory, pink, maroon, blue, red, whatever cards are ever issued. And, in the mean time -- deport all that are found. Period.
One must properly motivate the Left. By making deportation, provable, first, they'll maybe try at controlling the border -- even add eliminate voter fraud.
Sadly, the GOP is all hot air and tanning booths and such with Baleful Bawling Boehner sniffling away.