Conversation so far:
Did Rudy hold a political position when Rudy Giuliani was running for senate in 2000?
Republican.
Was Rudy still a mayor when he was running for senate?
Due to term limits, Giuliani could not run in 2001 for a third term as Mayor.

Question: Who was his Democrat opponent for this race?
Self-contained rewrite: Who was Rudy Giuliani Democrat opponent for U.S. Senate race?