With a tense confirmation hearing for Gina Haspel to run the CIA expected on Wednesday, dozens of defenders from both parties have pulled out the stops to support her nomination process.

More than 50 former top national-security and intelligence officials who know her directly, including six former CIA directors, three former directors of national intelligence and two former secretaries of state, signed a letter supporting her nomination, The Wall Street Journal reported. The group includes former Secretary of State Henry Kissinger as well as John Brennan, who led the CIA under President Barack Obama.

Haspel, who would be the first woman to lead the CIA, is the first career operations officer to be nominated to lead the agency in decades. She served almost entirely undercover, and much of her record is classified. Democrats say she should be disqualified because she was the chief of base at a covert detention site in Thailand where two terrorism suspects were subjected to waterboarding, a technique that simulates drowning. Critics say the practice is torture.

A source told Fox News Monday that the CIA dropped off binders of Haspel’s classified record from her 33-year career at the agency, including her performance reviews.

The source said all senators eventually will have access to the binders.

Haspel's involvement in the agency's interrogation programs after the Sept. 11 attacks has drawn scrutiny from Democratic lawmakers, who on Monday asked that the CIA’s Rendition, Detention, and Interrogation program be declassified in advance of the Senate Intelligence Committee hearing.

Haspel has told lawmakers in recent weeks that she would stand firm against any effort to restart the brutal detention and interrogation program. She is expected to reiterate that publicly this week.

The Journal reported her willingness to help the CIA evolve beyond its post-9/11 interrogation techniques led to the group letter of support. The paper also cited her insider role, saying supporters called her an important shield against a president who has been openly skeptical of the intelligence community.

Haspel will return to Capitol Hill to meet with more senators Tuesday, an intelligence official told Fox News.

Fox News' Jason Donner, Catherine Herridge, Chad Pergram and The Associated Press contributed to this report.