Bush needs Democratic votes - lots of them - in both chambers, to get this thing passed. I don't know what calculations you are making.
He also needs Conservatives in the GOP. Nothing is going to get passed. Tancredo and King just laid down a line in the sand ... no amnesty. Like the Miers debacle ... we Conservatives will win in the end. The cards 'Rats in the Senate hold are nothing. Bush is now on record as an obstructionist. The border problems will get worse. Blame it on the 'Rats.