for them to be getting, that they'll end up doing better. >> reporter: trump's tax proposal resembling the plans of two of his rivals, jeb bush and marco rubio, who also call for lowering the top income tax bracket and reducing rates for businesses. the billionaire candidate says any lost revenue would be offset by growing the economy and ending tax loopholes for wealthy hedge fund managers. but no specifics were provided to judge that claim. >> i actually believe they'll do better because i think the economy will grow. it will grow rapidly. and we'll have something very special. >> reporter: trump's policy roll outcomes as ben carson surges in the polls. now running neck and neck with the real estate mogul. >> i'm just going to be who i am. if people like that, that's great. and if they don't, so be it. >> reporter: carson climbing to 20% in the latest nbc news/"the wall street journal" poll essentially tied with trump at 21%. also moving up, carly fiorina and marco rubio tied for third at 11% a piece.