Speakers at the national meeting of the American Association for Advancement of Science expressed concern Sunday that some scientists in key federal agencies are being ignored or even pressured to change study conclusions that don't support policy positions.

The speakers also said that Bush's proposed 2005 federal budget is slashing spending for basic research and reducing investments in education designed to produce the nation's future scientists.

And there also was concern that increased restrictions and requirements for obtaining visas is diminishing the flow to the U.S. of foreign-born science students who have long been a major part of the American research community.

Rosina Bierbaum, dean of the University of Michigan School of Natural Resources and Environment, said the Bush administration has cut scientists out of some of the policy-making processes, particularly on environmental issues.

"In previous administrations, scientists were always at the table when regulations were being developed," she said. "Science never had the last voice, but it had a voice."

Issues on global warming, for instance, that achieved a firm scientific consensus in earlier years and now being questioned by Bush policy makers. Proven, widely accepted research is being ignored or disputed, she said.

Government policy papers issued prior to the Bush years moved beyond questioning the validity of global warming science and addressed ways of confronting or dealing with climate change.

Under Bush, said Bierbaum, the questioning of the proven science has become more important than finding ways to cope with climate change.

One result of such actions, said Neal Frank of Rice University, a former director of the National Science Foundation, is that "we don't really have a policy right now to deal with what everybody agrees is a serious problem."

Among scientists, said Frank, "there is quite a consensus in place that the Earth is warming and that humans are responsible for a considerable part of that" through the burning of fossil fuels.

And the science is clear, he said, that without action to control fossil fuel use, the warming will get worse and there will be climate events that "our species has not experienced before."

Asked for comment, White House spokesman Ken Lisaius said, "The president makes policy decisions based on what the best policies for the country are, not politics. People who suggest otherwise are ill-informed."

Kurt Gottfried of Cornell University and the Union of Concerned Scientists said a survey of scientists in the U.S. Fish and Wildlife Service found that about 42 percent said they felt pressured to not report publicly any findings that do not agree with Bush policies on endangered species. He said almost a third of the Fish and Wildlife researchers said they were even pressured not to express within the agency any views in conflict with the Bush policies.

"This administration has distanced itself from scientific information," said Gottfried. He said this is part of a larger effort to let politics dominate pure science.

He said scientists in the Environmental Protection Agency have been pressured to change their research to keep it consistent with the Bush political position on environmental issues.

Because of such actions, he said, it has become more difficult for federal agencies to attract and retain top scientific talent. This becomes a critical issue, said Gottfried, because about 35 percent of EPA scientists will retire soon and the Bush administration can "mold the staff" of the agency through the hiring process.

Federal spending for research and development is significantly reduced under the proposed 2005 Bush budget, the speakers said.

"Overall the R&D budget is bad news," said Bierbaum.

She said the National Science Foundation funds for graduate students and for kindergarten through high school education has been slashed.

NASA has gotten a budget boost, but most of the new money will be going to space shuttle, space station and Bush's plan to explore the moon and Mars. What is suffering is the space agency scientific research efforts, she said.

"Moon and Mars is basically going to eat everybody's lunch," she said.

Frank said that Bush's moon and Mars exploration effort has not excited the public and has no clear goals or plans.

He said Bush's Moon-Mars initiative "was poorly carried out and the budget is not there to do the job so science (at NASA) will really get hurt."