No, in fact, that is not correct. The successor to the STS was in development, but a bit underfunded, and a bit behind schedule, so the anti-American Party of the Single Party State led by Zero himself deep-sixed it.
http://www.spacelaunchreport.com/sls0.html
Here’s what I’m looking at:
“[George H.]...asked his vice president, Dan Quayle, to prepare a major NEW space initiative. Bush announced what became known as the Space Exploration Initiative in a speech on July 20, 1989”
“There were SEVERAL unsuccessful initiatives during the Clinton administration to develop a replacement for the space shuttle as a way of carrying humans and cargo into space. Most notable was the X-33 single-stage-to-orbit program, which pushed the limits of technological readiness and ultimately was canceled without a test flight.” http://www.nasa.gov/50th/50th_magazine/10presidents.html
“When President Bush established his NEW space exploration policy to return humans to the moon” http://en.wikipedia.org/wiki/Constellation_program#President_Bush
I read those passages to mean that George H. Bush, Clinton and George W. Bush [and Obama as you’ve pointed out] all changed the goal/direction/focus of the Space Program.
A new goal/direction/focus will, at the minimum, require a reevaluation of the proposed hardware, or, more likely, require new hardware.
In my experience, engineering re-evaluation slows (stops?) current engineering efforts as management and senior engineers now have more on their plate.
And that, I think, is my point: Administrations changing the direction of the Space Program prevented the STS follow on.
Put another way: it took 5 years from approval to first flight of the STS. [http://en.wikipedia.org/wiki/Space_Shuttle_program]. If the follow on had been approved and funded during any of the previous Administrations, Obama couldn’t have cancelled it. A lifter follow on wasn’t developed because priorities kept changing.