The Anti-Defamation League said it will provide all presidential candidates with information on extremists and hate groups following Donald Trump’s admission that he didn’t know anything about former Ku Klux Klan leader David Duke.

In a statement Sunday afternoon, the ADL said its Center on Extremism, which monitors and exposes extremists and hate groups, is providing information about extremists, including to the Trump campaign, “so that all candidates can be fully aware of these individuals and have a more complete picture when determining whose endorsements they should accept or reject.”

In an interview that morning on CNN’s “State of the Union,” Trump told host Jake Tapper: “Just so you understand, I don’t know anything about David Duke, OK? I don’t know anything about what you’re even talking about with white supremacy or white supremacists,” Trump told Tapper.

Several days earlier, Duke had told his radio listeners they should vote and volunteer for Trump. The Republican presidential front-runner disavowed the endorsement hours after the “State of the Union” interview, for the second time in three days, after refusing to do so on the program.

Duke is a former Ku Klux Klan grand wizard and white supremacist who has publicly asserted that Jews control the Federal Reserve Bank, the U.S. government and the media.

ADL CEO Jonathan Greenblatt said in a statement issued by the ADL on Sunday afternoon that Duke is “clearly exploiting Mr. Trump’s candidacy to get publicity for himself and his hateful ideas.”

“The last thing we want is for white supremacists to use this campaign to mainstream their bigotry,” Greenblatt said. “It is imperative for elected leaders and political candidates like Mr. Trump and others in the public eye to disavow haters such as Duke and the other white supremacists who have endorsed his candidacy.

“By not disavowing their racism and hatred, Trump gives them and their views a degree of legitimacy. Even if it is unintentional on his part, he allows them to feel that they are reaching mainstream America with their message of intolerance.”