By Rebecca Savransky - 02-28-16 09:47 AM EST
"I don't know anything about David Duke," he said on Sunday morning on CNN's "State of the Union."
"I don't know anything about what you're even talking about with white supremacy or white supremacists."
Duke, a white nationalist and former Ku Klux Klan grand wizard, last week told listeners to his radio show that voting against Trump at this point would be "treason to your heritage." He encouraged his audience to vote and volunteer for the front-runner, saying they would meet people with "the same kind of mindset that you have."
The Anti-Defamation League called on Trump to "distance" himself from Duke and other white supremacists and "publicly condemn their racism."
But Trump said on Sunday that he knows nothing about Duke or white supremacists.
"You're asking me a question that I'm supposed to be talking about people that I know nothing about," he said, when asked if he would condemn Duke.
He said he would do research on the "groups" in question and would then decide if he would condemn them.
"I have to look at the group, I don't know what group you're talking about," he said. "You wouldn't want me to condemn a group that I know nothing about."
"I have to look."