A blog rebellion among scientists and engineers at Los Alamos, the federal government's premier nuclear weapons laboratory, is threatening to end the tenure of its director, G. Peter Nanos.
Four months of jeers, denunciations and defenses of Dr. Nanos's management recently culminated in dozens of signed and anonymous messages concluding that his days were numbered. The postings to a public Web log conveyed a mood of self-congratulation tempered with sober discussion of what comes next.
''Some here will celebrate that they have been able to run the sheriff out of Dodge,'' Gary Stradling, a veteran Los Alamos scientist who is a staunch defender of Dr. Nanos, wrote Tuesday on the blog.
''It might be a good idea,'' Mr. Stradling added, ''to shut down the celebration and form a work party to clean up Dodge City, because the new sheriff will if we do not.''
The blogging comes at a delicate moment in the 62-year history of Los Alamos. The University of California, which has helped run the laboratory for the government since the days of the Manhattan Project, faces close scrutiny in Washington as to whether its contract should be renewed. And resignations and fears of a mass exodus have recently roiled the waters. Some analysts believe that now, given the public outcry, the university will have to abandon Dr. Nanos in order to make a credible bid to keep its contract.
Dr. Nanos would not comment. A spokesman for Los Alamos, Kevin Roark, said false rumors of the director's resignation had circulated for months. Mr. Roark added that Dr. Nanos was extraordinarily proud of what he had accomplished at Los Alamos, which employs 14,000 people on an annual budget of $2.2 billion.
Mr. Roark called the vitriolic blogging unrepresentative of the majority of employees and said it often had the tone of a sophomoric Halloween prank. ''Everybody, I think, was a little surprised at how mean it got,'' he said.
Several outside experts said that the director's quick departure was inevitable and that the blog's attacks were playing a significant role.
''Nanos is leaving,'' said Greg Mello, the director of the Los Alamos Study Group, a private organization in Albuquerque that monitors weapons laboratories. ''The blog changed the climate, giving people an outlet they didn't have before.''
Blogs seem to be everywhere. But this one is unusual, in that the Los Alamos National Laboratory, isolated in the mountains of New Mexico, has a long history of maintaining the highest level of federal secrecy. The laboratory's very existence was once classified. Today, barbed wire rings many of its buildings, federal agents monitor its communications, and its employees are constantly reminded that loose lips sink ships.
The blog (www.lanl-the-real-story.blogspot.com) went public in January and since then has registered more than 100,000 visits, with more than half a million pages viewed and more than 5,000 comments. Discussions run on a variety of topics, from the sanctity of retirement benefits to the likely identity of the next contractor who will run Los Alamos.
Since most messages are anonymous, there is no way to know how many laboratory employees contribute to the blog. Even so, from the sheer volume, detail and differing styles of the messages, the number is clearly many more than a handful. The language, often studded with obscure acronyms, suggests that the authors have a deep knowledge of the laboratory's exotic culture.
Furious debate centers on Dr. Nanos, a retired vice admiral of the Navy who holds a doctorate in physics from Princeton and became the laboratory's director two years ago. Many bloggers criticize his decision to shut down most of the laboratory in July, when he cited ''egregious'' safety and security violations after two computer disks with secret information were reported missing and an intern working with a laser suffered an eye injury. The security alarm turned out to be a clerical error -- the disks, in fact, never existed. Still, Dr. Nanos kept many laboratory areas closed for nearly seven months, until late January. In that time, laboratory personnel worked on improving safety and security.
Dr. Thomas J. Meyer, a distinguished chemist and a member of the National Academy of Sciences who oversaw 2,000 employees as associate director of the laboratory's strategic research, resigned in October during the shutdown and afterward filed a long critique of the episode and the director's acts.
''He chose to transfer blame and intimidate individuals even with a staff that was often attempting to implement difficult and complex safety processes,'' Dr. Meyer said in his critique, which was posted on the blog. He called the director's treatment of laboratory employees ''vindictive and abusive.''
A banner atop the blog site sets the tone, asserting that the shutdown cost taxpayers ''approximately $850 million, an exodus of highly talented staff members, and the loss of untold millions of dollars of funding from customers who have taken their business elsewhere.''
Laboratory officials say the shutdown probably cost $120 million, and federal officials recently put the figure at $370 million.
Mr. Roark, the Los Alamos spokesman, said that the laboratory was worried about a recent spike in retirement inquiries. ''We're not anticipating a mass exodus,'' he said. ''But that doesn't mean we're not concerned about the possibility. We are.''
The blog's creator is Doug Roberts, a computer scientist who is a 20-year laboratory veteran. In an interview, Mr. Roberts said he was inspired to start the blog when he and his colleagues had their critical submissions to a forum on the laboratory's online newspaper rejected.
Mr. Roberts said it was impossible to know how many laboratory personnel contributed to the blog because it was set up to protect their identities, if so desired. He estimated the vocal population at 200 to 500 employees.
The blog runs a petition for Dr. Nanos's removal; it has garnered more than 100 posts, although most are labeled ''Anonymous.''
One who signed openly in February was Dr. Brad Lee Holian, a theoretical physicist who worked at the laboratory for 32 years. Dr. Holian retired a month later.
''People were feeling like they were in a pressure cooker,'' he said in an interview. ''Nanos is so abusive, not just to the general staff but his underlings. People were afraid to say anything. On the blog they could vent without fear of reprisal.''
Jeff Jarvis, who publishes BuzzMachine, a blog that focuses on media issues, said the Los Alamos site showed ''a new ethic of transparency'' that has come with the explosion of electronic self-publishing. ''It's not just the power of the blog,'' Mr. Jarvis said, ''it's the power of the citizen.''
The battle over Dr. Nanos comes as the University of California is considering whether to bid to renew its contract, which expires Sept. 30. Two leading space and military contractors, Lockheed Martin and Northrop Grumman, have announced an interest in running the laboratory.
Chris Harrington, a university spokesman, denied that Dr. Nanos was about to resign and defended him as ''clearly understanding the mission of the lab.''
Mr. Harrington added, however, that the university was doing ''a thorough review'' of its management options for a possible bid on the new contract.