WASHINGTON ? A controversial House NASA authorization bill that appeared headed for a floor vote today has stalled, and it appears unlikely the measure will be taken up before lawmakers leave town for a six-week summer break that begins Aug. 2.

House leadership aides said just before midnight July 29 that the bill, a three-year authorization that recommends funding the U.S. space agency at roughly $19 billion a year through 2013, would not be taken up today, and that it is very unlikely the measure will come to a vote before lawmakers head home to campaign in their districts.

Although the bill, H.R. 5781, would not actually fund NASA, it would set guidelines for how much Congress can spend on the agency?s programs. In June, House appropriators approved a $19 billion budget for NASA next year, but fenced off most of the agency?s $4.2 billion human space exploration budget pending enactment of an authorization bill.

The House Science and Technology Committee approved H.R. 5781 with strong bipartisan support July 22, sending forward a bill that authorizes only a small fraction of the $3.3 billion NASA sought to invest in a commercial crew transportation system over the next three years. The bill authorized $150 million through 2013 for commercial crew and another $300 million in the form of government-backed loans or loan guarantees.

The measure also would continue much of the work being done under NASA?s Constellation program, a 5-year-old effort to build new rockets and spacecraft optimized for lunar missions that President Barack Obama targeted for termination in his 2011 spending proposal delivered to Congress in February.

With little time remaining in the fiscal year that ends Sept. 30, House Science and Technology Committee Chairman Rep. Bart Gordon (D-Tenn.) sought to bring the measure to the House floor under suspension of the rules ? a move that prevents amendments to a bill and requires a two-thirds majority vote to pass. But Gordon encountered resistance from House members hoping to weigh in on the measure during floor debate. Rep. Adam Schiff (D-Calif.) and other House Democrats met with Gordon early July 29 to address concerns with key elements of the legislation.

?We had a good conversation about the difficult choices facing the agency and promised to continue to work together to reach consensus on the bill,? Schiff said of the meeting through a spokesperson July 29.

Schiff was one of 13 Democratic members of the California delegation who urged Gordon?s committee to restore funding for commercial crew and cargo initiatives and exploration technology programs requested in NASA?s 2011 spending plan.

?These reductions will have a serious effect on California?s workforce and economy, and that of many states,? they stated in a July 21 letter to Gordon. ?These are areas that should be the cornerstone of NASA?s new direction because they will drive innovation and job creation across the nation.?

Space Exploration Technologies Corp. (SpaceX), a Hawhorne, Calif.-based company that holds a fixed-price contract to deliver cargo to the International Space Station and has aspirations to launch crews as well, sent an e-mail blast July 29 asking supporters to urge lawmakers to vote no on H.R. 5781.

Further complicating the bill?s path to the floor, the House Science and Technology Committee made some last-minute changes to H.R. 5781.

The bill previously created federally backed loan guarantees for companies developing commercial crewed vehicles, but the committee dropped that provision after the Congressional Budget Office raised questions about the long-term cost of the program. In place of the loan guarantees, the committee added a $300 million grant program aimed at fostering commercial crewed systems, according to a July 28 copy of the suspension bill obtained by Space News.

In addition, the modified bill would prohibit NASA from laying off civil servants for at least six months following the bill?s enactment.

The International Association of Machinists and Aerospace Workers said in a July 29 statement that the organization supports the House version of the NASA authorization. However, two unions that represent NASA civil servants ? The American Federation of Government Employees and the International Federation of Professional & Technical Engineers ? issued a joint statement the same day opposing ?the far from non-controversial? bill ?in its current form.?

During a six-hour markup of the bill July 22, Gordon said the NASA authorization would create a balanced, sustainable manned space exploration program that allows the agency to live within its means.

?We are in tough economic times, and we cannot do it all,? Gordon said, adding ?some of the ?nice-to-haves? have had to be deferred, and worthy activities have been funded at lower levels than some of us would like.?

Off Capitol Hill, commercial space advocates were outraged that committee leaders sought to rush the measure to a floor vote.

?This bill is deeply flawed, and it would be totally inappropriate for it to be pushed through with no debate,? Bretton Alexander, president of the Commercial Spaceflight Federation, said in a July 29 e-mail.

The Planetary Society, an advocacy group dedicated to space exploration, said in a July 29 statement that the future of the space program is too important to rush through a controversial change in policy.

?There has been inadequate time to review and understand the implications of this new plan. Therefore, the Society urges the House leadership to wait until after the August recess to bring the bill to the House Floor, allowing a full and open debate and for amendments to improve the bill,? the Pasadena, Calif.-based group states.

This story was provided by Space News, dedicated to covering all aspects of the space industry.