According to Steven Weinberg's essay in "Lake Views", Bush's idea of returning to the Moon etc. was never anything but a smoke curtain, i.e., they wanted to can

According to Steven Weinberg's essay in "Lake Views", Bush's idea of returning to the Moon etc. was never anything but a smoke curtain, i.e., they wanted to cancel a number of scientific projects planned by NASA (e.g., an experiment aimed at detecting gravitational waves) but didn't want it to look bad. So they came up with this ploy of announcing we're going to Moon and Mars, and all the cost cutting was justified by saying that all other NASA efforts had to be deprioritized to focus on the president's vision, while in reality never even a half-hearted effort was made to make the vision any closer to reality.