He will, however, be doing something at the convention but declined to elaborate.
Using Twitter to contact the New York Daily News, Trump said, "I was asked to speak at the RNC but said no, because I will be doing something much bigger -- just watch!"
His plans will remain private at the request of the Mitt Romney campaign, Trump spokesman Michael Cohen told CBS News Friday, but noted Trump will play "a huge, huge role" that will "certainly be memorable for the convention goers."
"It's going to be unique, to say the least," Cohen said. "It's been something the Romney campaign has been contemplating for quite a period of time and for now, they've asked us not to talk about it until they decide to make it known to the public."
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