The National Space Society has an online petition out:

I encourage President George Bush and the U.S. Congress to provide the funding needed to safely resume flying our Space Shuttle fleet in support of the assembly and operation of the International Space Station. I also support accelerating investment in next-generation space launch technologies and systems to help us continue reaching for the stars.

While the text of the petition refers explicitly only to "space exploration" and support for the ISS and Shuttle, the op-ed from Brian Chase accompanying the NSS email on this topic goes further, to the real point of going to space:

Our exploration of space is just the first step, though. The mark of a truly spacefaring civilization is the day that ordinary citizens can decide whether to live and work on Earth or opt to live away from our planet. We have a long journey to reach that point, but the journey is worth the risk and the expense, and will yield enormous economic, scientific and commercial benefits along the way.