WASHINGTON -- Shortly before the House Benghazi committee ramped up its battles with the Department of Defense in its probe of the 2012 terrorist attack, the committee's own top lawyer admitted at least four times in interviews with military officials that there was no more they could have done on that tragic night.

That's according to a letter obtained by The Huffington Post that was sent Sunday to the chairman of the committee, Rep. Trey Gowdy (R-S.C.), from the top Democrats on the Benghazi panel and the House Armed Services Committee, Reps. Elijah Cummings (D-Md.) and Adam Smith (D-Wash.).

The Democrats are sending the letter after relations between the GOP-led Benghazi committee and military officials recently took a turn for the worse. The military accused the committee late last month of demanding increasingly frivolous interviews from irrelevant service members; Gowdy responded by calling that charge a "partisan attack."

But in Monday's letter, which includes four separate comments from Gowdy's recently departed chief counsel, Democrats say Gowdy's own staffer agreed with the military.

According to the letter, that staffer, former Gen. Dana Chipman, said in interviews with former Defense Secretary Leon Panetta and former Defense Department Chief of Staff Jeremy Bash that the department did all it could on that night when Ambassador Chris Stevens and three other Americans were killed.

"I think you ordered exactly the right forces to move out and to head toward a position where they could reinforce what was occurring in Benghazi or in Tripoli or elsewhere in the region," Chipman told Panetta in the committee's January interview with the former defense secretary, according to transcribed excerpts. "And, sir, I don’t disagree with the actions you took, the recommendations you made, and the decisions you directed.”

Chipman was similarly deferential to Bash.

"I would posit that from my perspective, having looked at all the materials over the last 18 months, we could not have affected the response to what occurred by 5:15 in the morning on the 12th of September in Benghazi, Libya," said Chipman, who himself served 33 years in the Army.

“I don’t see any way to influence what occurred there," he told Bash at another point. "But what I am worried about is we’re caught by surprise on 9/11, we’ve got nothing postured to respond in a timely manner — and you can debate what’s timely, what’s untimely, but nothing could have affected what occurred in Benghazi.”

ASSOCIATED PRESS Leon Panetta, center, testified to the Benghazi Committee on Jan. 8, 2016.

That interview was also in January. Chipman left the committee not long after. His statements appear to confirm the general findings of the eight previous investigations into Benghazi, which found flaws in readiness and coordination but no signs of wrongdoing. Those reports also repeatedly debunked rumors that the military was ordered to stand down.

But after Chipman's departure, the Defense Department noted in its recent complaint, requests to interview people based on things such as Facebook posts and allegations on talk radio shows started to spike.

Those commenters, on the air and online, generally seek to revive some sort of stand-down scenario. Gowdy has said that it's his obligation to seek out all sources of information, including from rank-and-file service members, not just the people who gave the orders that night.

In a statement provided by the committee, Chipman said he backed Gowdy's dogged pursuit of fresh witnesses, although he did not contradict his comments mentioned in the Democrats' letter.

"I agree with Chairman Gowdy. If some witnesses refer the committee to other witnesses, the responsible thing to do is interview them," Chipman said. "The committee has an obligation to the American people to determine what can and cannot be substantiated, so if an individual makes public allegations about Benghazi, the committee should interview that person.”

A spokesman for the committee, Matt Wolking, added that the letter and the excerpted statements from the general were more examples of the Democrats' partisan attempts to curb the real progress the probe is making.

“No matter how many dishonest letters Democrats waste time writing, Republicans will continue conducting a thorough, fact-centered investigation that includes all relevant witnesses, regardless of rank," Wolking said.

He also argued that the committee has made progress, despite the minority party's efforts.

"Democrats have peddled the same politically motivated, predetermined conclusions from the very beginning, so it’s no surprise they’re still clinging to their false claim everything has been ‘asked and answered,’ even after the Pentagon admitted the map it previously provided to the committee showing the forces available on the night of the attacks was incomplete," Wolking said. "Democrats’ false attacks on legitimate congressional oversight are proof they’re nervous about the new information committee investigators have uncovered.”

Chipman is not the first former staffer to cause heartburn for Gowdy. A military investigator who was fired from the committee accused it of running a "partisan investigation."

The Benghazi committee has been working for more than two years and has cost about $7 million and counting. Democrats estimate that other government entities have spent about $13 million more responding to the committee's requests.

And while it's interviewed some 100 witnesses, its most notable revelation has been that then-Secretary of State Hillary Clinton conducted her State Department business on her personal email server. The FBI is investigating whether she violated any laws.

This story was updated to include comments from Chipman and the committee.