Ex-Washington Post fact-checker Glenn Kessler conceded on Thursday that he was "completely wrong" to label the COVID-19 lab leak theory "doubtful" in 2020.In an interview with Kessler, theeditors.com founder Ira Stoll brought up the eroding trust in fact-checkers from conservatives, using the 2020 Washington Post fact check titled "Was the new coronavirus accidentally released from a Wuhan lab? Its doubtful." as an example.Kessler defended the work done on the piece by his Fact Checker video team but blamed himself for the backlash for adding the words "its doubtful" to the headline.He described being called out by co-author Sarah Cahlan after it was published.CREDIBILITY CRISIS: MEDIA FACT-CHECKERS WERE EAGER TO DEBUNK COVID LAB LEAK THEORY, HAD TO ISSUE CORRECTIONS"One of the reporters on the piece came up to me the next day and said, I think you made a real mistake by putting 'it's doubtful' here. Because I'm uncertain where it stands, and you framed it in a way that made it seem more definitive than what we came up with," Kessler recalled.He continued, "That's on me. I screwed up. She recently left the Washington Post to go to another place. In my goodbye remarks, I mentioned, this explains why you should always listen to Sarah, because she's right, and I was completely wrong about this."Kessler argued that the fact check primarily focused on the claim that the coronavirus was a bioweapon rather than whether the virus came from nature or a lab."It's the headline. The piece itself..." Kessler said."People only remember the headline," Stoll interrupted."Like I said, that's on me," Kessler replied.Fox News Digital reached out to The Washington Post for comment but did not immediately receive a response.WASHINGTON POST ISSUES 'CORRECTION' ON 2020 TOM COTTON STORY CLAIMING COVID LAB-LEAK THEORY WAS 'DEBUNKED'The original fact-check claimed that scientific evidence at the time "strongly supports" the theory that COVID-19 came from nature and that "too many unexpected coincidences" would have been needed for a lab leak. However, it added that the Chinese government was unwilling and unable to offer more information on the theory.Though Kessler now says the fact-check mostly focused on bioweapon claims, he wrote on Twitter, now known as X, in 2020 that it was "virtually impossible" for COVID-19 to have come from a lab in a comment to Sen. Ted Cruz, R-Texas, about the piece."I fear @tedcruz missed the scientific animation in the video that shows how it is virtually impossible for this virus jump from the lab. Or the many interviews with actual scientists. We deal in facts, and viewers can judge for themselves," Kessler wrote.Kessler wrote a new fact-check in 2021 that the lab leak theory "suddenly became credible" after new evidence emerged. Though several members of the first Trump administration expressed support for the theory in 2020, Kessler blamed them for his rejection of their claims."The Trump administration also sought to highlight the lab scenario but generally could only point to vague intelligence. The Trump administrations messaging was often accompanied by anti-Chinese rhetoric that made it easier for skeptics to ignore its claims," Kessler wrote.CLICK HERE TO GET THE FOX NEWS APPThe Washington Post was among the earliest news outlets to reject the lab leak theory outright, calling it a "coronavirus conspiracy theory that was already debunked" in February 2020.