Republican presidential front-runner Donald Trump is drawing criticism for refusing to denounce an implicit endorsement from former Ku Kluz Klan leader David Duke.

Donald Trump waves to supporters at a campaign rally in Bentonville, Arkansas. (Photo by Benjamin Krain/Getty Images)

Trump said he doesn't know anything about him.

Florida Senator Marco Rubio has been using the matter to hammer Trump ahead of the Super Tuesday primaries.

Trump sure knew about Duke in 2000, when he cited Duke as one of the fringe elements of the reform party.

Trump blamed Duke for one of the reasons refused to run for president at that time.