Obama may be the first candidate in recent memory to get a “negative” bounce from his convention.
Believe it or not, Kerry did just that in 2004 (get a negative bounce) - at least from gallup.
http://www.gallup.com/poll/109702/Conventions-Typically-Result-FivePoint-Bounce.aspx
Of course, I’m all for Obama and Biden improving on that...to a -5 bounce. :-)