I don't think it matters. I noticed this morning that ACORN is involved in these rallies. ACORN is the group that conducts all those (Dem-sponsored) "non partisan" voter registration drives. They've been caught in many fraud schemes.
(Google: "ACORN voter registration fraud")
Now they're going to do voter registration drives among the illegals. What's to stop their registering non-citizens? Nothing. Most registrar's offices rely on the voter signing a sworn statement that he's elligible. That's it. So ACORN will register (perhaps millions of) new voters and the registrar offices will just go along.
Once they're registered to vote, it won't matter what happens in the Senate or with Bush. The Dems will have surrepticously acheived their true goal.