If the president tonight repeats the line that illegal aliens are doing jobs Americans won't do (which is simply false and offensive), or that we can't deport 12 million illegal aliens (as if that's the only option to discourage illegal immigration), or waters down the purpose and usefulness of putting Guardsmen on the border (they won't actually be patrolling the border), he will not be able to recover on this issue — which could mean his presidency won't recover either.  

Americans generally, and conservatives in particular, believe in the rule of law, national security, the integrity of our borders, and assimilation into an American culture.  These ought not be controversial views.  The American people reject interference by the Mexican government in the formulation of U.S. immigration policy.  And they're insulted by protests of illegal aliens and their supporters demanding citizenship and voting rights.

There's a fundamental disconnect between the elites in politics, business, the media, and the labor movement and the sentiments of the general public.  Tonight the president will announce with which side he stands.