David Duke, a white nationalist and former Ku Klux Klan grand wizard, is urging the listeners of his radio program to volunteer and vote for Donald Trump.

"Voting for these people, voting against Donald Trump at this point is really treason to your heritage," Duke said on the David Duke Radio Program Wednesday, 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."

Duke then urged his followers to call Trump's campaign headquarters to volunteer.

"And I am telling you that it is your job now to get active. Get off your duff. Get off your rear end that's getting fatter and fatter for many of you everyday on your chairs. When this show's over, go out, call the Republican Party, but call Donald Trump's headquarters, volunteer. They're screaming for volunteers. Go in there, you're gonna meet people who are going to have the same kind of mindset that you have."

Earlier in his broadcast, Duke called Trump's victories in Nevada and South Carolina a "historic day."