Updated

The Obama administration says it will provide some but not all of the materials a Senate committee wants on last year's Fort Hood shooting rampage, an "affront" to Congress' Constitutional obligation, according to two lawmakers.

The Senate Homeland Security and Governmental Affairs Committee had demanded that the Pentagon share documents and witnesses about the deadly incident by Tuesday morning.

An unusual Senate subpoena sought material the Pentagon claims would jeopardize prosecution of the suspect, Major Nidal Hasan. The U.S. Army psychiatrist has been accused of killing 13 people in November at Fort Hood, Texas.

Sens. Joe Lieberman, I-Conn., and Susan Collins, R-Maine, said they were disappointed that the Obama administration failed to comply with the subpoenas.

"Having sought DOD’s and DOJ’s voluntary compliance for the past five months since the Committee launched its investigation, we were forced to issue subpoenas for the most critical witnesses and documents related to how the government handled information about Major Nidal Malik Hasan before his alleged attack," the lawmakers said in a statement.

"DOD and DOJ have produced a limited set of documents in response to the subpoenas, which we appreciate.  However, they still refuse to provide access to their agents who reportedly reviewed Major Hasan's communications with radical extremist cleric Anwar al-Awlaki and to transcripts of prosecution interviews with Hasan's associates and superiors, which DOD already provided to its internal review.

"DOD and DOJ's failure to comply with the subpoenas is an affront to Congress's Constitutional obligation to conduct independent oversight of the Executive Branch, a right all the more critical in order to ensure that our government operates effectively to counter the threat of terrorism."

Senators have said they want to be sure the Pentagon is working to prevent similar tragedies.
Committee spokeswoman Leslie Phillips said that "as far as we're concerned they have not complied with the subpoena." She said the panel is considering its next step.

The Pentagon and Justice Department sent a letter to the committee Tuesday morning that Pentagon press secretary Geoff Morrell said lays out a compromise.

The committee would be able to read Hasan's personnel file and a secret addendum to the Pentagon's internal report on how the Pentagon failed to head off the shootings despite concerns over Hasan's behavior and apparent religious radicalization.

The committee would not be given access to witnesses in the case or to investigative reports that could be used at trial, Morrell said.

The administration also refused to let the committee have copies of the file and secret addendum because their release might jeopardize Hasan's prosecution.

"We have made a very good faith effort to try to find a middle ground," Morrell said.

The administration also offered additional briefings to select senators about the activities of an anti-terrorism task force that reviewed tips about Hasan.

"This is as far as we're prepared to go," Morrell said.

The Associated Press contributed to this report.