This has been an issue ever since Fox visited here just prior to 911 and they held the joint press conference that sent chills down the spine about open borders. I think a lot of people thought the issue was dead and buried after 911 only to find out what those of us here in the SW knew first hand -- the people South of the border didn't care a whit about 911 and had packed their bags and headed North to greener pastures; apparently with their governments help/approval and a wink and a nodd from the USA.
GW has been pushing for amnesty for illegals from his first election. It was heading for passage and then 9-11-01 attacks hit.
That put it on the back burner. The next year, it was pushed again, got through the House (IIRC) and almost got through the Senate. A Senator stopped it, on a technicality. That Senator was Robert Byrd, D-WVA. Had he not stopped it, it would have passed.
It was quietened for the '04 election cycle. Shortly after the election, it was put on the front burner, and here we are....