I'd bet on Rudy Giuliani, but other possibilities include Condoleezza Rice, John McCain, former MT
Gov. and RNC Chariman Marc Racicot, Senate Majority Leader Bill Frist, MA
Gov. Mitt Romney, NY Gov. George Pataki, or CA
Gov. Ahhnold Schwarzenegger (Constitutional Amendment notwithstanding).
I wish Bush would have dumped Cheney for one of the above. Cheney brings nothing to the ticket, is loaded with political baggage, and will leave a vacuum in 2008. It's too late now, though.
Keynes is dead and we are living in his long run.