Businessman Herman Cain may not have raised as much money as his chief rivals for the Republican presidential nomination, but he's been able to advance based on one important edge: a big idea that voters can grab hold of.
One poll released this week shows Mr. Cain as the top choice of 27 percent of likely Republican voters, the most of any candidate. The NBC News/Wall Street Journal poll has Mr. Romney second at 23 percent and Governor Perry in third at 16 percent.
This comes even though Cain, a political outsider, hasn't built much of a money machine. In a statement released late Friday, his campaign said it has raised more than $2.8 million during the third quarter and has no debt. By comparison, Romney raised $14 million and Perry $17 million during the three months that ended Sept. 30. (The candidates are all filing official quarterly numbers by the end of Saturday.)
But what Cain is missing in campaign cash he's apparently making up for with his big idea.
Where Perry has lacked a compelling pitch in recent debates, and Romney has failed to add much to his solid base of support, Cain's 9-9-9 plan has carried him on an upward surge.
The plan calls for essentially scrapping the current tax code and installing a 9 percent tax on business income, a 9 percent tax on personal income, and a new 9 percent federal sales tax.
What's the appeal?
For starters, some political analysts say the 9-9-9 name reflects brilliant marketing instincts by Cain, whose food-industry career spanned from Coca-Cola to being chief executive of Godfather's Pizza.
The name conveys simplicity, and tax rates that are all in the single-digits -- a contrast with the current code.
Cain has also framed his proposed tax overhaul as a solution for two national problems at once: a shortage of jobs and government run amok. He says the tax reform would help unleash a private-sector jobs recovery, while also streamlining a labyrinthine tax code that for many has become a symbol of government dysfunction and special-interest influence.
Another reason: Whether conservative voters like the details of Cain's plan or not, its boldness has served to energize public debate about radical tax code reforms – including the question of whether the government should rely more on consumption taxes and less on income taxes.
This doesn't mean that Cain has had nothing else going for him during his recent surge.
He says he has gained popular support from his outsider status as (until now) a nonpolitician. He has also drawn on oratorical skills honed as a broadcaster to connect with voters.
But the 9-9-9 plan has played a central role.
"The 9-9-9 plan that I have proposed is simple, transparent, efficient, fair, and neutral," Cain said in a recent presidential debate.
A key question is how many Republican voters will agree, and whether the plan's appeal will persist as it gets a closer look.
For all its positives in the eyes of many Republican voters, various concerns about the plan have been raised by other candidates and by independent economists.
The plan would end up raising taxes on many lower-income Americans, critics say, because of its emphasis on a sales tax and because the 9 percent tax on income would outweigh Cain's offsetting elimination of payroll taxes. At the same time, it would amount to a big tax cut for high-income Americans.
Questions have also arisen about whether the plan will bring in as much federal revenue as Cain claims it will.
Another problem: Some backers of dramatic tax reform say a national sales tax should not be created alongside an income tax, because that would give Congress extra ways to tax Americans more in the future by boosting rates.
Some conservative thinkers propose instead that the income tax should be eliminated altogether. Cain has backed that concept as a next phase of his plan – but that hasn't wholly defused this criticism.
Many economists support the general direction in which Cain moves: Broadening the "base" for tax revenue by eliminating deductions and loopholes, lowering tax rates to help spur business investment in the US, and considering a shift toward relying more on taxing consumption rather than income.
But as the bipartisan Bowles-Simpson Commission showed last year, those ideas can be pursued in configurations other than "9-9-9."
The campaign terrain could well shift again, with some pundits saying Cain might just be "flavor of the month" in the race.
Cain's rise has left Perry, in particular, scrambling to revive his campaign. He rolled out one piece of a new economic plan Friday, centered on developing US energy supplies.
Romney, for his part, was pressed by Cain in a recent debate on whether his 59-point economic plan is simple and efficient.
Romney fought back with a simple-isn't-always-best defense. "In my view, to get this economy going again, we're going to have to deal with more than just tax policy and just energy policy, even though both of those are part of my plan."