Donald Trump is stepping back from comments he made over the weekend when he claimed to know nothing about former Ku Klux Klan leader David Duke, saying that he couldn't hear the questions clearly.

Trump was asked Sunday on CNN's State of the Union whether he rejected support for his presidential campaign from the former KKK Grand Dragon and other white supremacists after Duke told his radio followers this week that a vote against Trump was equivalent to "treason to your heritage."

"Well, just so you understand, I don't know anything about David Duke. OK?" Trump told host Jake Tapper. "I don't know anything about what you're even talking about with white supremacy or white supremacists."

Trump's rivals for the Republican presidential nomination, senators Ted Cruz and Marco Rubio, went after him Sunday following the comments.

Cruz responded on Twitter, telling Trump: "You're better than this. We should all agree, racism is wrong, KKK is abhorrent."

Rubio went further in a message to thousands of supporters in Leesburg, Va.: "We cannot be a party who refuses to condemn white supremacists and the Ku Klux Klan," Rubio said. "Not only is that wrong, it makes him unelectable. How are we going to grow the party if we nominate someone who doesn't repudiate the Ku Klux Klan?"

On Monday, however, Trump told NBC's Today that he was given a "very bad earpiece" for the interview and that he "disavowed David Duke all weekend long on Facebook and on Twitter."