She admitted in the FBI interview she had read reports of Russian efforts to compromise voter data and wondered why the information she possessed wasn't public.
"I saw the article and was like, 'I don’t understand why this isn’t a thing,'" she said. "It made me very mad. I guess I just didn’t care about myself at that point. Yeah, I screwed up royally.
"Seeing that [information] that had been contested back and forth in the public domain for so long, trying to figure out, like, with everything else that keeps getting released and keeps getting leaked -- why isn't this getting -- why isn't this out there? Why can't this be public?"
In the interview, Winner first says she had left the documents on her desk before putting them in a burn bag to dispose of them. After the agent presses her with specifics, including the location where she sent them, Winner admitted she took the documents out of the building and mailed them to the media.
Winner described the incredibly low-tech way in which she managed to abscond with the classified information. When asked by the FBI how she got the documents out of the office, she responded, "Folded in half in my pantyhose."
Winner told the agent there was no security stopping her from lifting the information.
"Let's be straight -- there's little to no security on documents," she said. "Nobody pats you down."
The FBI interviewers noted few people had printed out the document Winner lifted from the facility.
"The most likely candidate, by far and away, is you," the interviewer said. "Now, I don't think you are, you know, a big bad master spy, OK? I don't. ... Now, I'm not sure why you did it, and I'm curious as to that, but I think you might've been angry over everything that's going on, politics-wise."
CNN singled out a Twitter account believed to belong to Winner -- she used her own photo as an ID and posted selfies -- in which she complained about Donald Trump winning the presidency.
She is facing at least nine years in prison if the case goes to trial and she's found guilty.
Winner worked as a translator -- she speaks Farsi, Pashto and Dari -- at Fort Gordon in Augusta, Georgia.
ABC News' Pierre Thomas and Jack Date contributed to this story.