Presidential candidates Obama and McCain never talked about illegal immigration. The reason: they agreed about immigration. Both candidates favored "comprehensive immigration reform" - code words meaning a sort of amnesty for the 12 million or so illegal immigrants now in the country.
Republicans have argued they can get a substantial portion of the Hispanic vote if they favor "comprehensive immigration reform." McCain conclusively proved these arguments wrong. He was known for his support of immigrant rights, never spoke about illegal immigration and still got relatively few Hispanic votes.
So...we are left to wonder in what ways the contest just ended would have had different contours if one of the candidates, probably the Republican, had made an real issue of illegal immigration. Is it possible a tough stance on illegal immigration would have given the Republican access to more of the blue collar workers who were once so-called Reagan Democrats? A reasonable argument can be made that this is the case, but now we will never know.