On the day he revised his tax plan to 9-0-9, Republican presidential candidate Herman Cain signs a supporter's "999" sign after unveiling his "Opportunity Zone" economic plan in front of the Michigan Central Station, an abandoned train depot in Detroit.
Left to right: Former Sen. Rick Santorum; Rep. Michele Bachmann; former House Speaker Newt Gingrich; former Massachusetts Gov. Mitt Romney; Rep. Ron Paul; former Minnesota Gov. Tim Pawlenty; entrepreneur Herman Cain.
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