The first thing that comes to mind is that the question of Edwards' experience will be raised. Part of his reply could be something like:
'If I recall correctly, part of the reason Mr. Cheney was on the ticket in 2000 was to reassure those who thought Mr. Bush didn't have enough experience. Well look where the Vice President's experience has gotten us... secret meetings to determine our country's energy policy, no bid contracts with his former company, warnings that if my running mate is elected then we'll have a terrorist attack, etc, etc'.
Can you think of any?