At a news conference in Texas on Friday, Donald Trump said he disavows the support of white nationalist and former Ku Klux Klan grand wizard David Duke.

"I didn't even know he endorsed me. David Duke endorsed me? I disavow, OK," Trump said.

Duke, who has expressed his support of Trump's message on immigration throughout the election, urged his radio listeners on Wednesday to volunteer and vote for Trump.

"Voting for these people, voting against Donald Trump at this point is really treason to your heritage," Duke said, referring to Ted Cruz and Marco Rubio. "I'm not saying I endorse everything about Trump, in fact I haven't formally endorsed him. But I do support his candidacy, and I support voting for him as a strategic action. I hope he does everything we hope he will do."