Re: Leo: okay, yes, I can believe he knew Josh would want to find his own candidate (who couldn't be Russell) and this couldn't happen had Josh been promoted to Chief of Staff.

More on the stability: I think you're right about Josh's relationship with Bartlet. Also seems likely that Leo knew that Josh is a clingy person, by nature, and loyal to an actual fault. Putting him in the CoS job would have meant Josh would have rode it to the very end whereas Leo always meant for him to go on to other things.

I should dig up some old posts from when this was current, but I was briefly excited by the thought they'd pick Toby. Now, Toby would have been a miserable CoS, but he always seemed to be the foreign policy heavyweight to Josh's domestics.