EDIT
Since it first moved into the White House seven years ago, the Bush administration has resisted efforts to treat CO2 as a pollutant that is largely responsible for global climate change. But the Supreme Court ruled a year ago that carbon dioxide from burning fossil fuels is subject to the Clean Air Act. If such emissions are a danger to public health and welfare, the court said, the EPA must regulate them – in particular, emissions from motor vehicles.
EPA staffers came to that conclusion, according to the Los Angeles Times. "EPA staffers told the Times they had concluded that such greenhouse gases were a major threat to water supplies, crops, wildlife, and other aspects of public welfare, and their finding was forwarded to the White House for review in December. In addition, under orders from Johnson, the staff last fall completed a draft regulation to reduce greenhouse gas emissions from vehicles."
Still, Johnson chose to move slowly. Critics say it was in response to industry pressure. The New York Times editorialized: "… the administration – despite all the blather about Mr. Bush's newfound awareness of the dangers of climate change – has again refused to do anything about the problem, wasting another year in a struggle in which time is no one's friend."
Congressional Quarterly reported that Representative Markey wants to subpoena the EPA for its failure to turn over documents related to global warming, including the EPA's draft proposal to regulate greenhouse gas emissions.
EDIT
http://www.csmonitor.com/2008/0403/p17s01-sten.html