Kristen Hellmer, of the Council on Environmental Quality, part of the Executive Office of the US President, said the CEQ had been cooperating with Congress. When asked about allegations of political interference in scientific documents, she said: "We do have in place a very transparent system in science reporting."
As to the force applied on people who speak out on global warming:
"After that speech and the release of data by Dr Hansen on December 15 showing that 2005 was probably the warmest year in at least a century, officials at the headquarters of the space agency repeatedly phoned public affairs officers, who relayed the warning to Dr Hansen that there would be 'dire consequences' if such statements continued, those officers and Dr Hansen said in interviews," the Times reported.
Full article Hansen works at NASA. You know, the place you can't say "Big Bang" without adding, "It's just a *theory*, you know."
Granted, New Scientist is not the source I would like it to be, but the articles are properly linked out to their sources.