WASHINGTON – In a rare public dispute between a Democratic-led Congress and the White House, a Senate committee Monday subpoenaed the Obama administration for secret documents and access to witnesses in last year’s mass shooting at the Fort Hood Army base in Texas.

The chairman and ranking Republican of the Senate Homeland Security and Governmental Affairs Committee have alleged that the Obama administration is covering up critical details about the case, including whether the government had access to information that could have prevented the shooting.

“Unfortunately, it is impossible for us to avoid reaching the conclusion that the departments simply do not want to cooperate with our investigation,” wrote Sens. Joseph Lieberman, I-Conn., and Susan Collins, R-Maine, in a letter accompanying the subpoena.

The Defense and Justice departments say that release of the disputed data would compromise the prosecution of Maj. Nidal Hasan, the Army doctor charged with killing 13 people.

“We’ll obviously be reviewing it and determining the department’s next steps,” Pentagon spokesman Bryan Whitman said of the subpoena.

Some of the dispute boils down to technicalities. The Defense Department has already given temporary access of some personnel files to the Senate Armed Services Committee because it oversees personnel issues within the Defense Department.

Defense officials said because the Homeland Security committee lacks jurisdiction over personnel issues, the department has not granted its request for access to Hasan’s personnel files.

The case of Hasan has been of particular interest to lawmakers because of his suspected ties to foreign terrorists and his promotion through the military’s ranks despite repeated concerns over his performance and behavior.

A Defense Department review concluded that several unidentified medical officers failed to use “appropriate judgment and standards of officership” when reviewing Hasan’s performance as a student, internist and psychiatric resident.

Last week, Defense Secretary Robert Gates said the Pentagon would provide Congress with any information it could so long as the information wouldn’t hurt the prosecution’s case.

Gates also has issued new regulations, including restrictions on how privately owned guns can be carried or stored at military installations. Hasan had little or no access to military firearms in his job as a psychologist, but was able to buy two handguns and bring them onto the base.