I’m sure it depends on where one lives.
If assimilation were official government policy, in two generations there would only be a gnat’s ass difference between the bulk of both groups. And from that, as long as there are economic opportunities, a similar political breakdown as exists among the broader American populace (40% conservative 30% moderate 20% liberal 10% clueless).
I understand that the heritage of most Mexican illegals is Amerindian from lower classes (Mexicans like the Germano-Basque Vicente Fox are doing just fine over there), but many are mixed and have already become more American than not (see even George Lopez, for example). By the 2nd or 3rd generation, most will not even speak Spanish that well or at least only use it around family and friends of a similar hispano background.
Point being, that bright line being drawn by the media is not even remotely definable.