https://www.allsides.com/news-source/factcheckorg-media-bias
Some, including nonprofit Capital Research Center, have accused FactCheck.org of being biased to the left.
"[FactCheck.org's] parent organization, the Annenberg Public Policy Center, was established by Walter H. Annenberg, the former publisher of TV Guide and the Philadelphia Inquirer, President Richard Nixon’s ambassador to Great Britain, and a Republican. But over time the organization moved to the left," Capital Research Center writes in an article about "Dishonest Fact Checkers."
Capital Research Center writes that Annenberg Public Policy Center’s director, Kathleen Hall Jamieson, recruited Brooks Jackson (a former reporter for Associated Press, Wall Street Journal, and CNN) to found FactCheck.org. Jamieson "has also served on the board of the Center for Public Integrity, a left-leaning investigative journalism nonprofit that receives funding from left-wing hedge fund manager George Soros."
Capital Research Center says that FactCheck.org has "not been brazenly partisan, despite being very much a creature of the mainstream media. It has taken Democrats to task on a number of fronts," but that both FactCheck.org and Politifact go "far beyond what they say they do, claiming to fact-check subjective things like political rhetoric that are not susceptible to fact-checking."