I've seen this claimed repeatedly, but no authoritative evidence, and I am not convinced. Was Proxmire really that famous as anti-space crusader by May 1961 (minus however long the story was in the pipeline – it is ironic that its publication more or less coincided with JFK's "before this decade is out" address; its description of NASA indeed fits its more modest and slower beginnings) as he became a decade or two later? His Wikipedia entry, nor anything else I've been able to Google up, does not shed any light on this.
So, I'll appreciate any details on
- the story's (pre)history
- Proxmire's early career as relates to this issue.
Fun fact: Google Books shows that the story was reprinted in 1973 NASA Authorization, Hearings Before the Committee ... U. S. House of Representatives, after it was invoked by two leaders of the "Federation of Americans Supporting Science and Technology", actually just university students. No specific reference to Proxmire was made there.