People's opinions can change

My gallup poll link shows that yes, attitudes have changed but is a) not a sea change (sentiment has been this way since the 1880's) and the poll b) does not break the results down by race, that is, the poll does not account for the rising US Latino population.

Addendum: By the way, I take politians' stance on immigration with a grain of salt. If history is any guide, these politicians will condemn illegal immigration faster than you can say, "voter discontent."

House Speaker Nancy Pelosi, 2008: “We do need to address the issue of immigration and the challenge we have of undocumented people in our country. We certainly do not want any more coming in.” Source.

House Speaker Nancy Pelosi, 2009: The latest House bill leaves in place nearly all the loopholes of the previous bill, H.R. 3200. Illegal immigrants will be able to gain health care at taxpayer expense through these loopholes (and we aren’t talking emergency care, which remains untouched and available, and isn’t even an issue). We’re talking health coverage, paid wholly or substantially by U.S. taxpayers. Source.

I grant you the two are not completely in-line but it's like saying, "we should do everything to keep robbers out of our house but since they're here we should serve them dinner on our neighbor's dime."

The point is that while the economy's bad these guys are all about anti-immigration. When the economy is good they're all about open borders. Meanwhile, you, me, and your kids get screwed no matter what the economy (increased competition, poorer education facilities, larger classrooms, strain on healthcare system, etc.).