"This is about trust, and the public is not being afforded an open and honest debate about the nominee," Heinrich told NBC News.
"There are questions that absolutely need to be answered publicly, and given her position, she can make the choice to do so. As the nominee, she owes that to the public."
Heinrich sits on the the Senate Intelligence Committee, which will hold a hearing Wednesday on Haspel's nomination.
Democrats have pressed the CIA to declassify more documents that would provide information on Haspel's years at the agency.
Trump has touted Haspel as a "highly respected nominee" and accused Democrats of trying to obstruct her nomination process because she is “too tough on terror.”
“My highly respected nominee for CIA Director, Gina Haspel, has come under fire because she was too tough on Terrorists,” Trump said Monday.
“Think of that, in these very dangerous times, we have the most qualified person, a woman, who Democrats want OUT because she is too tough on terror. Win Gina!”
The president tapped Haspel to be the agency’s new director when he nominated former Director Mike Pompeo to be the new secretary of State.
The White House in recent days has increased a public relations campaign to support Haspel’s nomination.
Haspel herself reportedly considered backing away from her nomination at the end of last week, for fear it would hurt the CIA, before reconsidering.