The anonymous senior Trump administration official who authored the infamous New York Times op-ed in 2018 declaring to be part of the "resistance" revealed himself on Wednesday to be former Department of Homeland Security chief of staff Miles Taylor

Taylor, who previously came forward as a critic of President Trump and a supporter of Joe Biden in August, explained that he wrote his 2019 book "A Warning" as Anonymous as a "caution to voters that it wasn't as bad as it looked inside the Trump administration – it was worse."

"While I claim sole authorship of the work, the sentiments expressed within it were widely held among officials at the highest levels of the federal government," Taylor wrote in a statement published on Medium. "In other words, Trump's own lieutenants were alarmed by his instability."

Taylor was hired by CNN as a contributor in September. However, it is now known that he lied to the network by denying authorship of the op-ed during an Aug. 21 interview with his now-colleague Anderson Cooper. 

ANONYMOUS OFFICIAL BEHIND INFAMOUS NYT OP-ED TO RELEASE BOOK ON TRUMP WHITE HOUSE

"There was an op-ed, there was a book by someone calling themselves 'Anonymous.' Are you aware of who that is?" Cooper asked. 

"I'm not," Taylor responded. "Look, that was a parlor game that happened in Washington D.C. of a lot of folks trying to think of who that might be. I've got my own thoughts about who that might be, but-"

"You're not Anonymous," Cooper interjected. 

"I wear a mask for two things, Anderson: Halloweens and pandemics. So, no," Taylor answered. 

Taylor similarly lied to Vice News political correspondent Elizabeth Landers about being the anonymous writer. 

According to CNN anchor Jake Tapper, who broke the news on his network on Wednesday afternoon, "We did not know this until today."

CNN did not immediately respond to Fox News' request for comment, though a spokesperson told Washington Post's Erik Wemple that Taylor will remain as a contributor despite his lie to Anderson Cooper. 

White House Press Secretary Kayleigh McEnany released a statement knocking Taylor as a "low-level, disgruntled former staffer," as well as "a liar and a coward who chose anonymity over action and leaking over leading.

"He was ineffective and incompetent during his time as DHS Chief of Staff which is why he was promptly fired after only serving in this role for a matter of weeks," McEnany added. "It is appalling a low-ranking official would be granted anonymity and it is clear the New York Times is doing the bidding of Never-Trumpers and Democrats."

TRUMP CLAIMS HE KNOWS IDENTITY OF ANONYMOUS ADMINISTRATION OFFICIAL WHO PENNED SCATHING TELL-ALL

White House Chief of Staff Mark Meadows also piled on the former Trump official. 

You have got to be kidding me. Miles Taylor? That’s who the New York Times granted an anonymous editorial article? I’ve seen more exciting reveals in Scooby-Doo episodes. What a monumental embarrassment," Meadows tweeted. 

When the op-ed by a "senior Trump administration official" was published in September 2018, there was plenty of speculation that the identity was actually someone of high status. Names that were floated at the time included then-White House Chief of Staff John Kelly, then-Counselor to the President Kellyanne Conway, then-DHS Secretary Kirstjen Nielsen, and then-U.N. Ambassador Nikki Haley. 

The big reveal turned out to be a big letdown on social media. 

"It’s an embarrassment," Axios reporter Jonathan Swan reacted. "I also didn’t realize the definition of 'senior administration official' could be *this* expansive. Wasn’t even an agency chief of staff at the time the op-ed ran."

"I can’t stop laughing. What a bust. Everyone is like 'who?'" former acting DNI Ric Grenell tweeted. 

ANONYMOUS ‘A WARNING’ AUTHOR GIVES TINY CLUES TO IDENTITY, CHALLENGES TRUMP SUPPORTERS

"So 'anonymous' turns out to be both no one you've heard of and a CNN contributor. Who could've predicted this," RealClearInvestigations senior writer Mark Hemmingway similarly said.

"This is like Al Capone's vault. The guy quit the administration, was heavily promoted through a clear PR campaign ... did media tours, and is now making $$ as a CNN contributor. What a coward. It's a reminder of how much of the Never Trump crowd is made up of grifters," NewsBusters managing editor Curtis Houck wrote. 

"Miles Taylor is the new James Comey. He’s not a hero to either side," journalist Yashar Ali declared. 

Other critics noted Taylor's tenure at DHS coincided with the Trump administration's controversial policy of separating children of migrants from their parents at the U.S.-Mexico border.

"Miles Taylor was a critical part of the team that decided to separated thousands of migrant kids from their parents, resulting in lifelong psychological trauma. He would like you to believe otherwise," MSNBC correspondent Jacob Soboroff said. 

"Congrats to all of the #resistance people who bought a book by a guy who was complicit in DHS family separations," New Yorker's Josh Billinson quipped.

The Times itself also came under fire for granting Taylor's request to publish the op-ed under the byline of "Anonymous." In a note attached to the piece, the paper said it had taken "the rare step" because, "We believe publishing this essay anonymously is the only way to deliver an important perspective to our readers."

"The term we chose, senior administration official, is used in Washington by both journalists and government officials to describe positions in the upper echelon of an administration, such as the one held by this writer," deputy editorial page editor Jim Dao explained at the time.

Critics, however, disagreed with the view of Taylor as an "upper echelon" member of the Trump administration.

"There’s a legitimate role for anonymity in journalism but that op-ed embodied one of its worst uses, where you obscure the source of information primarily to make the source sound more authoritative than he really is," Vox senior correspondent Matthew Yglesias tweeted. 

"The revelation of the identity of 'Anonymous' calls into question whether the NYT had ample grounds to allow him to write without identifying him. I figured it had to be someone at cabinet level, at least," Washington Post columnist Karen Tumulty similarly expressed. 

CLICK HERE TO GET THE FOX NEWS APP

"Is an advisor to a cabinet secretary really a 'senior administration official'? The widespread impression at the time of the NYT op-ed was that 'Anonymous' was someone who actually advised the president," ABC News Chief White House correspondent Jonathan Karl posted. 

A spokesperson for the Times told Fox News, "We take seriously our obligations to protect sources. Many important stories in sensitive areas like politics, national security and business could never be reported if our journalists violated that trust. In this case, however, the writer has personally waived our agreement to keep his identity confidential. We can confirm that he is the author of the Anonymous op-ed. We don’t plan to comment further." 

Fox News' Sam Dorman and Andrew O'Reilly contributed to this report.