Despite the controversies, Perry remains a serious Republican contender, analysts say. He collected $17 million in seven weeks for his campaign and has a record of winning big elections.
"Perry has not cratered," said Brown. "This is Cain's moment in the sun. If Cain begins to fall, logic suggests his supporters might well go to Perry."
Cain remains largely unknown. While Romney and Perry blasted each other's records at recent debates, no one seriously challenged Cain.
That may change.
Cain fits a pattern that's been apparent all year, said David Paleologos, director of the political research center at Suffolk University, which surveys New Hampshire voters.
"We've now had four instances of Republicans surging," he noted, as conservatives seek an alternative to the more centrist Romney.
None of the alternatives has shown staying power. Businessman Donald Trump and former Arkansas Gov. Mike Huckabee, chose not to run. Minnesota Rep. Michele Bachmann won the August Iowa straw poll, but support has plunged in recent weeks. Perry, who led some national polls a month ago, has fallen behind Romney in some surveys.
Romney is expected to discuss his 160-page economic plan, released a month ago. It stresses familiar conservative themes, such as keeping tax rates low, spurring domestic energy production, easing regulatory burdens and repealing the 2010 federal health care law.
Cain is likely to be asked about his 999 plan, which would impose 9 percent flat tax rates on businesses, individuals and sales.
But how viable is the plan? Will it stand up to criticism from rivals? And most important, will it seem reasonable to voters?
Aitken, like so many voters, wants to know more. "He seems like a very nice guy, and he's inspirational," she said. "but he doesn't have a record to go on. We have to go on what he's saying."
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