The Register survey, long considered the most reliable of Iowa polls, finds the former Godfather's Pizza executive with 1-point advantage in the state, leading the former Massachusetts governor 23 percent to 22 percent.
Ron Paul trailed in third place, with 12 percent support. The remaining 2012 hopefuls were in single digits, including Michele Bachmann (8 percent); Rick Perry (7 percent); Newt Gingrich (7 percent); Rick Santorum (5 percent) and Jon Huntsman (1 percent).
The poll has a margin of error of plus or minus 4.9 percent.
Cain's popularity has soared in the state, in spite of the fact he's done little actual campaigning there. But Romney's numbers are equally surprising, given the ex-governor has visited the state just three times since launching his second White House bid this spring.
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