Now what was the name of that piece he co sponsored? Aaah, yes...it was the S. 970: Iran Counter-Proliferation Act of 2007.
Now, if I do recall, the same piece of legislation contained a section that went something like this:
(8) The Secretary of State should designate the Iranian Revolutionary Guards as a Foreign Terrorist Organization under section 219 of the Immigration and Nationality Act (8 U.S.C. 1189) and the Secretary of the Treasury should place the Iranian Revolutionary Guards on the list of Specially Designated Global Terrorists under Executive Order 13224 (66 Fed. Reg. 186; relating to blocking property and prohibiting transactions with persons who commit, threaten to commit, or support terrorism).
http://www.govtrack.us/congress/bill.xpd?bill=s110-970