Fox News’ Chris Wallace has previously failed to fact-check Republican presidential nominee Donald Trump’s brazen lie that he opposed the Iraq War, raising further concerns about how Wallace will moderate the third and final presidential debate.

Wallace has twice before let Trump lie about his opposition to the Iraq War -- a claim that has been proved false time and time again. On February 21, when Trump appeared on Wallace’s Fox News Sunday, Wallace let the candidate say he “was against” the Iraq War “at the beginning” while offering no pushback; and on March 13, Wallace again let Trump’s claim that he “was against the war in Iraq … I’m one that said don’t go in” go unchallenged.

Wallace’s complicity in enabling Trump’s lie is troubling given that he has been tapped as moderator for the final debate between Trump and Democratic nominee Hillary Clinton and that he has said it’s not his “job to be a truth squad” when moderating. Trump took the news that Wallace wouldn’t fact-check the candidates during the debates well, telling Larry King, “I can understand him saying that. … I think that the candidates should police themselves.”

Wallace’s previous disregard for Trump’s recurrent lie is even more concerning given the conflict of interest tethered to Wallace’s role as a moderator. As Media Matters founder David Brock wrote to the Commission on Presidential Debates, former Fox CEO Roger Ailes’ position advising both Trump and Rupert Murdoch -- the head of Fox’s parent company and Wallace’s boss -- represents a “glaring conflict of interest” that infringes on the credibility of any Fox News moderator. Brock has asked the commission to reconsider Wallace as a moderator.

Given NBC host Matt Lauer’s heavily criticized, fact-challenged moderation during a national security forum -- where he, too, let Trump lie about his previous Iraq War stance -- it’s crucial that the debate moderators stamp out Trump’s mendacity and ensure a fact-based debate.