There’s a big, big difference between Bush Sr and Bush Jr’s programs.
First, Bush Sr. basically just threw the notion out there without doing any planning. So NASA came back with a pie-in-the-sky plan worth 450 billion dollars, that had everything but the kitchen sink in it.
Second, Bush Sr tried this 14 years ago. Space technology has advanced quite significantly since then. You wouldn’t know it from looking at the shuttle program, but advanced in computing, AI, propulsion, materials, and other critical technologies are quite substantial. We’ve actually flown advanced engines on working missions - successfully.
Finally, Bush’s Dad was a waffler who was pushed around a lot. Bush Jr. does what he says.
As for budget concerns, one of the beauties of this new plan is that it doesn’t require a lot of new funds, because it gets the money by scrapping existing programs. Specifically, the Shuttle and ISS. Bush plans to kill the Shuttle completely once ISS is finished, and he plans to get the U.S. government out of the ISS by 2013. Those two programs consume about 6.5 billion a year. Another 1.8 billion in other spaceflight initiatives will be rolled into the new program, which means that, without NASA getting another nickel in funding it could put over 8 billion a year into this program. Since the program is over 15 years long, that alone gets you over 100 billion, which should be enough to get you a base on the moon.
But Bush wants to kick in an additional 800 million next year to set up the program, and give NASA 5% increases per year. Over 15 years, that’s what, another 20 billion or so?
I think it’s doable. And I also think it’s something Congress might go for, because they don’t have to sign off on massive new funding, it gets them to look like they’re doing something new and bold while actually lowering risk (if they do nothing and another Shuttle fails, it’ll look very bad. If they vote for this and another Shuttle fails, it’ll just look like they were right to vote for cancellation of the program).
This isn’t something that was just cooked up for the election, by the way. The wind has been blowing towards this since Bush took office. He started off right away boosting NASA’s budget, and directing them to start work on advanced power supplies and propulsion methods (project Prometheus), which obviously has direct application to the new program. If you notice, Dick Cheney has been conspicuously absent of late - it turns out he was spearheading a secret commission that has been working on this plan for quite a few months now. It’s not a throwaway line for the State of the Union or to give Bush the “Vision Thing” - it’s a major part of his administration’s planning.
The major wrench that could be thrown into the works here is NASA and its culture. I’m not convinced that NASA still has the ability to do something this audacious. NASA has failed at almost every major new manned system they’ve tried to build.
I also expect Bush to involve a lot of private industry - perhaps to take over the LEO role - running the ISS, building LEO rockets, etc.