(CNN) The top Democrat on the Senate Intelligence Committee is asking the Justice Department to provide former federal prosecutor John Durham's investigative report into the destruction of CIA interrogation tapes ahead of CIA director nominee Gina Haspel's confirmation hearing next month.

Virginia Sen. Mark Warner sent a letter Tuesday to Attorney General Jeff Sessions requesting the report that Durham — who was tapped as a special prosecutor to investigate the 2005 destruction of the CIA tapes — prepared when deciding not bring any charges in 2010 over the incident.

Haspel's role in the tapes' destruction, which was ordered by her boss, then-head of the CIA clandestine service Jose Rodriguez, is one key sticking point for senators over Haspel's nomination to be the first female head of the CIA.

In his letter, which was obtained by CNN, Warner noted that last week, the CIA declassified a report from former acting CIA Director Mike Morell that absolved Haspel of wrongdoing.

"In light of the CIA's decision to release the internal investigation into the destruction of interrogation video tapes, I believe the Durham report would be helpful to understand Ms. Haspel's role," Warner wrote.

Warner's request for the Justice Department report is the latest volley in a push from Senate Democrats on the Intelligence Committee to make public Haspel's record over a 33-year CIA career that was spent almost entirely undercover.

The CIA has released bits and pieces about Haspel's career ahead of her confirmation hearing next month, including a detailed biography as well as the Morell report.

But Democrats have argued that's far from sufficient, and three Intelligence Committee members — Sens. Dianne Feinstein of California, Ron Wyden of Oregon and Martin Heinrich of New Mexico — have sent the CIA multiple letters demanding more information about both the tapes incident as well as Haspel's time running a CIA "black site" in Thailand where harsh detainee interrogations were conducted.

Jaime Cheshire, the CIA's director of congressional affairs, sent a letter to the three Democrats Tuesday that said the CIA would work with the Intelligence Committee "to provide access to the full Senate in appropriate classified forums."

The letter said that Haspel's confirmation "requires increased transparency with the American public," although it did not detail specifics about what information would be provided. The letter also noted that the CIA makes an effort to protect clandestine officers who work on overseas missions.

"This is especially true for our most senior officers who have the highest public profile and, therefore, could be at highest security risk, a risk that does not subside even when they leave public service," Cheshire wrote.

The response did little to satisfy the Democrats' demands.

"Ms. Haspel is not an undercover operative, she's the deputy CIA director seeking a Cabinet-level position," they said in a joint statement. "It's unacceptable for the CIA to hide her behind a wall of secrecy, particularly when such secrecy is unnecessary to protect national security. Concealing her background when no sources and methods are at stake shows nothing but contempt for the Senate and the public."

Senate Intelligence Chairman Richard Burr, a North Carolina Republican who did not sign onto Warner's letter Tuesday, argued that Morell's report should resolve any concerns senators have about Haspel's role in the destruction of the CIA tapes.

"We've had the deputy of the CIA at the time, fully (covered) whether the special prosecutor looked at it, and what they said," Burr told CNN. "You can continue to ask for information, but that cleared it up. They found her not guilty of anything."

Haspel was Rodriguez's chief of staff and drafted the cable ordering the destruction of the tapes in 2005. Morell's report found that Haspel drafted the cable under instruction from her boss, and he ultimately made the decision to destroy the interrogation tapes. The report also found that Haspel incorrectly believed at the time that Rodriguez would seek approval from then-CIA Director Porter Goss before moving forward.

Senators are also looking for more information about Haspel's role supervising the Thailand site, but Burr that said he didn't believe the CIA could take that step.

"The ones Wyden wants, there's no way they can ever be declassified," Burr said. "You can't declassify a program that doesn't publicly exist."