From: A Young Illinois Reader [Email him ]
One of the remarkable things about immigration discourse is how little effort the Left makes to pretend to care about national sovereignty. The principles of the Democrats on immigration (to the degree that either party can be said to operate on principle) are hostile to limits on immigration.
Much of the Left believes that it is wrong to deport people,  or even to prevent economic migrants  from entering in the first place. Not just impracticable, expensive, or difficult, but wrong. The arguments they make in favor of accommodation of today's illegals militate for precisely the same approach to tomorrow's migrants and would-be migrants. "They come here to work,"  "It's the American  dream," "You can't split up families ," "We need population growth ," etc. These arguments do not admit of any limiting principle and would be just as valid after "comprehensive immigration reform" a.k.a. amnesty  as before.
Moreover, the Democrats give very little indication that they share an immigration patriot's view of the social contract. They don't seem to believe that government is constituted by and for the citizenry, or that its policies should not prejudice the fortunes of citizens in favor of those of foreigners. The American nation-state is an empty vessel to them, an expedient in the service of a borderless ideology.
These are not necessarily ridiculous things to believe, and I'm sure some otherwise fine and decent people have such views.
The question, however, is why Republicans would ascribe one iota of credibility to the Left's commitments to border security or internal enforcement of immigration laws in the wake of an immigration deal. Sincere liberals would have a moral obligation to ignore and reject such measures going forward. (Insincere liberals would do likewise, albeit for the crasser motives of Treason Lobby votes  and Cheap Labor Lobby  money.)
Again, we are confronted with the stupid/evil dichotomy.  Establishment Republicans are terrible negotiators. Or, like Democratic pols bargaining with public sector unions, they simply don't care about the interests of the constituents they're supposed to be representing.