July 30, 2010 at 6:34 PM ETThe showdown over America's space policy will have to wait until September at the earliest: House Democrats had considered rushing through passage of a $19 billion NASA authorization bill today, before the start of Congress' August recess. But the leadership decided instead to keep the bill in limbo, in part because Democratic members from California protested. One factor might have been the strong opposition to the House version of the bill that came from advocates of space commercialization. The House bill would have made deep cuts in the Obama administration's request for $6 billion over five years to support the development of private-sector spaceships capable of bringing crew to the International Space Station. However, that's only one factor. Revisions in the measure, sparked by the Congressional Budget Office's criticism of a proposed loan guarantee program for launch companies, complicated efforts to suspend House rules and fast-track the bill to a vote by the full House. What's more, two unions - the American Federation of Government Workers and the International Federation of Professional and Technical Engineers - came out with a jointly written letter that sharply criticized the House bill for its "many serious shortfalls." They urged lawmakers not to try pushing it through. Meanwhile, on the other side of the debate, the International Association of Machinists and Aerospace Workers sent a letter strongly supportive of the House bill. The Machinist union's website also referred to an independent report that raised questions about the Obama administration's space commercialization initiative. The Senate's space legislation is currently seen as a compromise between President Barack Obama's original plan and the House version. The best realistic outcome, at least the way most space commercialization advocates see it, would be for the Senate's version to prevail. But it's clear that the debate over America's future space effort is just warming up - and that there's plenty of processing yet to be done in the sausage factory on Capitol Hill. For further details on today's twists and turns, click on over to Space News' explanation as well as the Space Politics blog and RLV and Space Transport News. Join the Cosmic Log corps by signing up as my Facebook friend or hooking up on Twitter. And if you really want to be friendly, ask me about "The Case for Pluto."