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Speaking with Fox News host Sean Hannity in a radio interview on Tuesday, O'Keefe said he had accrued the unaired footage inside CNN's newsrooms from employees, according to reports from the network itself and The Huffington Post.
He also alluded to releasing the obtained footage "WikiLeaks-style," or in systematic batches. Some of the footage is scheduled to be released on Thursday afternoon, O'Keefe said. He said it centers on "one corporation, multiple newsrooms."
O'Keefe's planned exposé follows a tenuous month during which President Donald Trump, his staff, and allies have devoted much airtime in criticizing and labeling CNN as "fake news."
"My audience, the American people, are deeply upset at the media," O'Keefe told CNN in a telephone interview. "We think our media needs to be held to account, and CNN is kind of the leader of that. CNN has a very important role as an arbiter of news."
"This is all legally recorded information," he said.
The purported leaks also come after O'Keefe's statements from last month's pre-inauguration party dubbed the "DeploraBall." At the event, he said he planned on "going after the media next" and even called his footage "CNN Leaks."
"We are inside their newsrooms," he said, according to Politico. He added he had spies "embedded in your institutions."
O'Keefe has built a reputation of using questionable methods to secure recordings and has been accused of selective-editing practices during his video investigations. He first gained notoriety in 2009, after releasing undercover videos that alleged illegal activity by employees of the Association of Community Organizations for Reform Now (ACORN), a nonprofit organization that advocated for issues like voter registration.
One employee sued O'Keefe, alleging he broke the law by taping without consent. O'Keefe ended up settling the case for $100,000. The videos led to the federal defunding of the group. ACORN later filed for bankruptcy.