A recent spate of polls showed Cain joining Mitt Romney and Rick Perry in the top GOP tier.
Cain said Sunday that his signature 9-9-9 tax plan would lower taxes for most Americans, but conceded some middle-class-Americans might pay more. The plan would scrap the current federal tax code and replace it with 9% rates for personal income and corporate taxes and add a 9% national sales tax.
Many independent analysts say Cain's plan would lower taxes on the rich and raise them for many middle class Americans, but the Georgia businessman disputed those doubts on NBC's "Meet the Press."
