"Apprentice" boss Donald Trump says confusion between his show and "The Apprentice: Martha Stewart" is to blame for his show's lower ratings this season.

Trump told ABC Radio his numbers for Thursday night's "The Apprentice" on NBC are "still good," even though audience levels are down about 40 percent this season.

"The numbers are still good," Trump said. "I think there was confusion between Martha's 'Apprentice' and mine. Mine continues to do well, and as you know, the other one has struggled severely."

Stewart's spinoff has "struggled mightily" against ABC's hit series "Lost," Trump said, but he refused to predict what may happen to Stewart's spinoff down the line.

"That's really up to (producer) Mark Burnett and myself and NBC," he said.

Trump said shooting is already under way for a fifth season of his show.

"It'll be very interesting," he said. "I think it's a very good show."