It was a former member of the Republican administration, however, who complained in July that "the nation's doctor" has been marginalized. Carmona said political appointees in the Department of Health and Human Services prevented him from speaking out on scientific evidence tied to embryonic stem cell research, contraception and sex education.
His statements echoed other allegations of political interference with science this year:
•A Fish and Wildlife Service inspector general's report last month revealed how a political appointee altered scientific reports on endangered species in ways that limited protected habitats, and released internal reports to real estate industry lawyers in violation of federal regulations. Agency director H. Dale Hall called the actions "a blemish" on its scientific integrity.
•NASA climate scientist James Hansen testified in March before a House committee about how a 24-year-old press liaison, a political appointee, barred him from speaking publicly about global warming. "Review and editing of scientific testimony by the White House Office of Management and Budget seems to now be an accepted practice," he added.
•Weather researcher Thomas Knutson of the National Oceanic and Atmospheric Administration told the Senate in February how appointees forbade him from commenting on links between hurricanes and global warming.
"Anything that doesn't fit into the political appointees' ideological, theological or political agenda is often ignored, marginalized or simply buried," Carmona testified.
Says science historian Steven Shapin of Harvard: "There never was a time when science was perfect and politics was 100 miles away." But the Carmona testimony suggests "something markedly intrusive and shameless about what the administration is up to."
In interviews, three administration science officials, Ray Orbach of the Energy Department's Office of Science, William Jeffrey of the National Institute of Standards and Technology and Elias Zerhouni of the National Institutes of Health, denied that administration officials have distorted scientific advice.
Research proposals for federal money are evaluated by scientists themselves, and this peer review "is probably the strongest bulwark against politics interfering with science," Zerhouni says.
Says Marburger: "I have not seen any orchestration or central direction about what you can't talk about." The president expects scientists to share their expertise and to "be a little bit proactive in getting the truth out" if they encounter resistance, he says.
That's not quite the whole picture, critics say.
"The only reason the truth is getting out now is that a new Congress is holding Bush's feet to the fire," says Chris Mooney, author of The Republican War on Science. Mooney says the administration's leaders have long discouraged scientists.
Says Daniel Greenberg, a Washington journalist who has written extensively on science policy: "The Bush administration has interests — ideological, theological and compliant to some industries — that are its preoccupations. Scientists have an inflated sense of themselves if they think the administration has anything against them in particular as it pursues its goals in ways that disregard their views."