A leading U.S. Senate Democrat accused the Bush administration on Tuesday of a cover-up" aimed at stopping the Environmental Protection Agency from tackling greenhouse emissions. "This cover-up is being directed from the White House and the office of the vice president," said Sen. Barbara Boxer, the California Democrat who chairs the Senate Environment and Public Works Committee. At issue is a preliminary finding by the EPA last December that "greenhouse gases may reasonably be anticipated to endanger public welfare," according to Jason Burnett, the agency's former associate deputy administrator who appeared at a news conference with Boxer. Such a finding would be an early step toward government regulation aimed at protecting public health. Boxer said that unless EPA documents were released, it was likely that within the next two weeks her committee would try to subpoena the material. Burnett, who resigned on June 9, told Boxer's committee the White House tried pressuring him to retract an e-mail [in] which he detailed the finding. Burnett said he refused. Since then, the EPA finding has been left "in limbo." [Boxer] has been trying since last October to obtain related documents to show that planned congressional testimony on global warming by Dr. Julie Gerberding, director of the Centers for Disease Control and Prevention, was censored by the Bush administration. Burnett told the congressional committee the administration's Council on Environmental Quality "and the office of the vice president were seeking deletions to the CDC testimony."