The Environmental Protection Agency's ability to regulate greenhouse gas emissions continues to be a political football. This week, the US House is preparing to pass legislation that would strip the agency of this authority and, in the process, it rejected an amendment that reiterated the scientific community's position on climate change. Meanwhile, the Senate has rejected a similar bill, suggesting that President Obama won't have to exercise his threat of a veto, at least for now.

The issue at hand is whether the EPA has the authority under the Clean Air Act to regulate greenhouse gasses as a pollutant, and if so, if there is a scientific case for doing so. Under previous administrations, the EPA had ignored states' requests to evaluate the latter, leading them to sue. In 2007, the Supreme Court ruled that the Clean Air Act compelled the EPA to make a scientific risk assessment. The Agency obeyed and found that greenhouse emissions were pollutants under the Act's definition. The Bush Whitehouse, however, instructed its staff not to open the e-mail containing these findings, leaving things in limbo (this document was later released by the current EPA).

The Obama administration's EPA came to the same conclusion, and this time the endangerment finding was published, and the EPA has been preparing regulations. The initial thought was that the threat of EPA action would spur Congress to exert its authority and pass comprehensive climate legislation. That hasn't worked out and, with Republicans in control of the House, the exact converse is taking place: Congress is seeking to amend the Clean Air Act to specifically block the EPA from regulating any greenhouse gasses.

The Republicans seem to be unaware that the EPA's endangerment findings also mention ocean acidification caused by elevated carbon dioxide, leaving it an alternate route to act on carbon dioxide emissions. The bill explicitly allows the regulation of greenhouse gasses due to environmental hazards other than climate change. This is especially ironic given that carbon dioxide would seem to be the primary concern of the bill's authors, who have labeled it the "Energy Tax Prevention Act of 2011."

As part of the legislative maneuvering ahead of the bill's likely passage, Democrats attempted to insert an amendment that recognizes the conclusions of scientific organizations such as the American Association for the Advancement of Science and the National Academies of Science. The amendment read, "Congress accepts the scientific findings of the Environmental Protection Agency that climate change is occurring, is caused largely by human activities, and poses significant risks for public health and welfare." It was rejected in a 184-240 vote.

Nevertheless, the legislation seems likely to be symbolic. Obama has threatened to veto it and the Senate has now rejected a similar bill on a vote that largely followed party lines.

Under normal circumstances, this might indicate that attempts to limit the EPA would await the next election. These are not normal times, however, as the US government may be shut down as early as Friday if the executive and legislative branches can't agree on a budget compromise. The House may use the budget negotiations to attempt to force Obama and the Senate to accept limits on the EPA simply to avert a government shutdown.