In your dreams! You don’t understand. Rush’s conservatism is part of his soul. Obama’s beliefs are contrived and he cannot articulate them unless he has a carefully crafted speech which he can read off of a teleprompter.
Believe what you like. Nevertheless, Obama's a politician who, for all his faults, has plenty of experience in actual head-to-head debate.
Rush Limbaugh can't compete at that level -- he's an entertainer who never has to yield the floor to anybody.
If they ever went through with a debate (which they won't), my money would be on Obama -- not only to win the debate itself, but also to win the media coverage afterwards.