http://www.washtimes.com/national/20070524-042017-1483r.htm
from above article:
"Now that this agreement has left the back room and is subject to the legislative process, we believe we will have opportunities to improve it in both the Senate and the House," said Janet Murguia, president of the National Council of La Raza (NCLR), a Hispanic rights group.
It's not just the overall bill that's drawing the calls. Yesterday, NCLR sent out an alert asking supporters to lobby their senators against two amendments that would tighten the bill and for another amendment that would expand family immigration.
(note "drawing the calls". They're toll free calls paid for by American taxpayers)