Robert Zimmerman has a post, with which I mostly agree. But since I seem to be unable to comment there, I would add a couple corrections.
Gagarin’s launch vehicle had reached escape velocity and orbited the earth.
No, it reached orbital velocity. If it had reached escape velocity, it would never have come back. Escape velocity is about 1.4 (root of two, to be exact) times local circular velocity.
Another point (besides the fact that the two Bushes aren’t Junior and Senior).
In all these declarations, it was assumed that the space vehicles and rockets to get into space would be designed and operated by the federal government.
That actually was not the case for the Vision for Space Exploration. If you go back and read the Aldridge report, it recommends commercial (and international) participation, and doesn’t require or expect NASA to develop any launch systems. It only directs it to build a “Crew Exploration Vehicle” (what eventually became Orion). All of the contractors for the Concept Exploration & Refinement trade studies considered existing commercial launchers, or larger versions of them, for the lunar architecture. No one considered anything resembling what became Ares, because it was universally recognized that a Shuttle-derived system would be unaffordable (not to mention that it was always a nutty idea). It was only when Mike Griffin replaced Sean O’Keefe and fired Craig Steidle that a Marshall-developed rocket became the baseline. In fact, other than eliminating the goal of moon first, the new NASA plans (or, at least, the 2011 budget submission) resemble the original VSE much more than Mike Griffin’s Constellation did.