WASHINGTON (Reuters) - The lawmaker behind a landmark congressional torture report on Thursday demanded the release of classified documents on past CIA interrogations before the U.S. Senate considers President Donald Trump’s nomination of Gina Haspel to lead the spy agency.

Slideshow ( 2 images )

Trump nominated Haspel, the Central Intelligence Agency’s deputy director, on Tuesday to become director. The announcement prompted objections from inside and outside government over her involvement in the CIA’s use of waterboarding and other “enhanced interrogation techniques” widely described as torture.

“As we move forward with the nomination process for Ms. Haspel, my fellow Senators and I must have the complete picture of Ms. Haspel’s involvement in the program in order to fully and fairly review her record and qualifications,” Democratic Senator Dianne Feinstein wrote in a letter to CIA Director Mike Pompeo and Haspel.

Trump on Tuesday nominated Haspel to succeed Pompeo, his choice to be the next secretary of state. [nL1N1QV0JE]

Feinstein’s opinion of Haspel is considered a key to her chances of being confirmed. Feinstein chaired the Senate Intelligence Committee when it produced a massive 2014 report describing the CIA’s harsh detention and interrogation programs.

A handful of Democrats have already said they would oppose Haspel. Senator Rand Paul on Wednesday became the first Republican to oppose her. [nL1N1QW149]

In 2013, Feinstein sought to keep the CIA from appointing Haspel as head of clandestine operations. But she has not come out against Haspel’s selection to be director, indicating that, while she had reservations, she was impressed by her performance as deputy director.

Haspel oversaw a secret CIA “black site” prison where detainees were tortured as the United States investigated the Sept. 11, 2001, attacks. Two suspected members of al Qaeda were subjected to waterboarding and other harsh interrogation techniques at the facility.

Haspel’s nomination could be at risk if there is enough of a groundswell of opposition to keep her from getting at least 51 Senate votes. Trump’s fellow Republicans control only a 51-49 seat majority in the chamber.

Haspel defenders say she was only following orders when drafting a cable ordering the destruction of the videotapes of the interrogations and that another official sent it without consulting her.

A former U.S. security official said Haspel appeared multiple times before a grand jury investigating the interrogation program but neither she, nor anyone else investigated for their role, was ever indicted.