Washington CNN  — 

Calls for details about what budget cuts the Defense Department is considering are coming from both houses of Congress and both parties. And they are getting more urgent.

The latest demand for specifics came in a letter Thursday from Sens. John McCain (R-Arizona) and Lindsey Graham (R-South Carolina) to Secretary of Defense Leon Panetta. “We ask that you describe the specific options and types of actions the department would be required to take” if more budget cuts are mandated.

Their letter went on to say “In order for the Congress to do its job, we cannot wait until December or later to receive specific and concrete information.”

Pentagon spokesman Capt. John Kirby confirmed that Panetta had received the letter and would reply, but wouldn’t say if that reply would include the details McCain and Graham were demanding.

Press Secretary George Little implied more work needs to be done before any specifics are shared with Congress.

“Before we get to particulars on what may be the impact of the initial round of cuts or the sequestration, we have a little bit more homework to do,” Little said. “We understand and value the importance of congressional oversight and congressional engagement on this matter. So we just have to let the process unfold.”

The McCain/Graham letter came one day after the House Armed Services Committee grilled the chiefs of staff for all four branches of service. Democratic Congressman

John Garamendi of California pressed the top brass for specifics: “What exactly can be cut? For example, do we need 5,300 nuclear weapons? Do we need a triad? Does the, does the Marine Corps really need a new expeditionary vehicle, or can we get by without a Marine Corps vertical takeoff F-35 version?” Garamendi said. “What exactly is going to happen? This committee needs to know and I certainly need to know. If any of you would like to respond with some specificity, I’d be very interested in hearing it.”

Air Force Chief of Staff Gen. Norton Schwartz responded, “The reality is that we all operate under certain limitations in the executive branch and that you, you can be frustrated sir, but this is the way it is. It’s not real until it’s the president’s budget.”

Without saying for certain that any final cuts had been decided, Schwartz did spell out some possible impacts of bigger budget decisions. “At a minimum, they would slash all of our investment accounts, including our top-priority modernization programs such as the KC-46 – the (air refueling) tanker – the F-35 Joint Strike Fighter, the MQ-9 remotely piloted aircraft, and the future long-range strike bomber.”

And Gen. James Amos, the Marine Corps commandant, said he is worried about more than hardware; he is concerned the cuts would mean a loss of some of the United States’ most experienced troops.

“We will lose that leadership of those NCOs,” Amos said referring to the possibility of a reduction in the overall number of Marines in the corps. “Those staff noncommissioned officers at the five-, six-, seven-year mark that have shouldered the burden of the last 10 years of our conflicts. We will lose that,” Amos said.

Though they may object to the lack of specifics from Defense, they are in total agreement with Panetta, who said widespread mandatory Pentagon cuts would have “devastating effects” on the Department of Defense. McCain and Graham wrote, “We could not agree more.”