Dwayne Day and Jeff Foust have an interesting history of recent (i.e., over the past several years, prior to the announcement of the VSE) internal human exploration studies at NASA, with some unanswered questions:

…who initiated the discussions in the White House concerning the need for a new human spaceflight goal and why? Who championed the issue and how much interaction did they have with NASA? Why and how did the White House pick and choose between plans? Why was NASA