NASA's top watchdog routinely tipped off department officials to internal investigations and quashed a report related to the Columbia shuttle explosion to avoid embarrassing the agency, investigators say.

A report by the Integrity Committee, a government board that investigates inspectors general, found that Robert Cobb "created an appearance of a lack of independence," and it questioned whether NASA would do enough to reprimand him.

NASA administrator Michael Griffin has proposed sending Cobb to leadership training and requiring that he meet regularly with department officials on how to improve, but that is not enough, said Integrity Committee Chairman James Burrus.

"All members of the committee believe that disciplinary action, up to and including removal, could be appropriate," he said in a previously unreleased report that also accused Cobb of abusing authority to create an "abusive work environment."

In responses to the Integrity Committee, Griffin defended Cobb in noting that he was being faulted for the mere appearance of a conflict of interest. Cobb has acknowledged he cultivated relationships in the department to build trust but said he never stepped over the line.

"This has been a trying year for Mr. Cobb and I have been impressed with his continued focus on his professional obligations to the Congress and to this agency," Griffin wrote. He said the report "does not contain evidence of a lack of integrity on the part of Mr. Cobb."

The report, completed Jan. 22 and made public this week by the House Committee on Science and Technology, threatens to renew questions of conflicts of interest and cronyism in a Bush administration under fire for allegedly exerting undue political influence in the firing of U.S. attorneys.

Only President Bush can dismiss Cobb, a former White House aide and 1986 law graduate whom Bush selected as NASA's IG in 2002. The White House has said it is satisfied with NASA's plans to require leadership training for Cobb, who once was an adviser on ethics to then-White House counsel Alberto Gonzales, now the attorney general.

But three key lawmakers who chair Senate and House subcommittees with jurisdiction over the space agency disagree. They are calling for Cobb's resignation and are pledging to pursue hearings if necessary to investigate his conduct.

"This inspector general's own peers — after months of investigation — found that he has abused his position of authority and lacked an appearance of independence from top officials at NASA," said Rep. Bart Gordon, D-Tenn., who chairs the Science and Technology committee.

Internal e-mails and documents made available Thursday paint a picture of Cobb as an IG more concerned with preserving cozy relationships than maintaining independence in the agency he is charged with overseeing.

The report found Cobb met then-NASA administrator Sean O'Keefe at least twice a month between 2002 and 2005 for private lunch meetings dubbed in calendar logs as "Administrator's Hideaway." Cobb also flew with O'Keefe on NASA aircraft, and eagerly accepted O'Keefe's golf invitations.

"What was the name of the guy who worked at the Naval Criminal Investigative Service that we played golf with at Belmont?" Cobb wrote in a Dec. 15, 2003, e-mail to O'Keefe.

Cobb also routinely sought O'Keefe's advice on how to structure audit investigations and he let O'Keefe review a draft IG opinion regarding the independence of the Columbia accident investigation.

At one point, the report said, Cobb went "ballistic" when he learned that the Texas Rangers were planning to release a "Crime Stoppers Report" to the public to announce an alleged theft of jewelry from Columbia astronaut Laurel Clark, whose ring was taken from her recovered remains. The Rangers and Cobb's office were conducting a joint investigation of the alleged ring theft. NASA employees said Cobb felt NASA would be embarrassed by any suggestion it had not properly safeguarded the remains.

In a meeting with one of his staff, Cobb, who demanded that a tape recorder in the room be shut off, said no report on the ring would be issued because the "whole NASA Columbia investigation was not going well, NASA wanted it finished, and for the outcome to reveal nothing that would make NASA look bad."

At other times, Cobb tipped off O'Keefe to various audits, including documents he planned to request and search warrants the FBI planned to issue.

"Please keep close hold," Cobb wrote in an e-mail June 16, 2004, regarding forthcoming warrants in an undercover operation targeting suppliers of bad parts to NASA.

O'Keefe replied: "OK — keep me posted. More incoming cowpies I suspect."

A year earlier, O'Keefe also teased Cobb after he broke a lunch appointment with him, suggesting he should "cool his jets" on investigations.

"Moose — sorry I stiffed ya for lunch today," O'Keefe wrote on May 6, 2003, referring to Cobb by his nickname.

Noting that he ran into the Securities and Exchange Commission chairman at the House Government Reform Committee, O'Keefe passed along the message: "His legis affairs rep advised as how I should tell our IG to cool his jets and get a life. Just repeating the comment."

In response, Cobb told the Integrity Committee he squelched the Columbia report because there was not enough evidence yet to substantiate whether a theft had actually occurred. He said he should not be faulted for the appearance of wrongdoing.

"I cannot control how people feel," he wrote.