Bush never had NASA on his front burner. But he commissioned the design and construction of the Ares system. Obama has no concrete plan to replace the shuttles. and the plan for the International Space Station is now to "DE-ORBIT" it in the tear 2015.
Familiar with the concept of "busy work"? It's when you do work that makes you look like you're achieving something hen you're just spinning your wheels. By setting tasks for NASA but not giving them the actual money to achieve anything is a prime example of busy work.
Secondly Ares is intended as a replacement for the shuttle so why should Obama set NASA the goal of designing the replacement - they've already got the thing on the drawing board.
Finally as pointed out in another thread, that design work Bush got NASA to do is turning in a total cluster fuck.