though you probably already found it by now:
* The subject of the proposed amendment was not about giving (or denying) Social Security benefits to illegal aliens; it was about whether a select group of formerly illegal workers (i.e., those who might obtain legal immigration status if the Comprehensive Immigration Reform Act of 2006 were enacted) should be able to receive credit for payments they made into the Social Security system using phony Social Security numbers (i.e., numbers that were invalid or had been assigned to others). Such persons would still be eligible to collect Social Security benefits in the future; they just wouldn't receive credit for payments they had already made into the system.
* The senators named didn't technically vote against Senator Ensign's amendment itself; they voted (by a 50-49 margin) in favor of a Motion to Table (i.e., a motion to permanently kill the pending matter and end any further debate on the subject).
* It was the potential passage of the Comprehensive Immigration Reform Act that created the situation Senator Ensign's amendment sought to prevent in the first place (i.e., allowing formerly illegal workers to receive credit for earlier Social Security payments), so the senators who ultimately voted in favor of the immigration reform act might logically be considered at least as responsible for the outcome as those who voted to table the Ensign amendment.
If all of the above made your eyes glaze over, it boils down to this: While the list of who voted which way is accurate, what was being voted on was a motion to table (that is, stick in a closet in hopes that it will never be seen again) a motion to deny former illegals credit for the Social Security payments they made while in the U.S. illegally.
http://www.snopes.com/politics/immigration/socialsecurity.asp