Views are more lopsided on Cain’s idea of setting the federal income tax, business tax and a national sales tax at 9 percent each. Americans by a 20-point margin, 56-36 percent, hold an unfavorable opinion of the 9-9-9 plan. And intensity runs against the idea: it’s seen “strongly” unfavorably rather than strongly favorably by a 3-1 margin, 35 percent vs. 12 percent. [...] The 9-9-9 plan, for its part, doesn’t win majority backing in any of these groups. It’s seen unfavorably by 50 percent of Republicans, rising to about six in 10 Democrats and independents alike.
Keep in mind that those responses are without any negative arguments being given against the plan. Imagine what the numbers would look like if people were told that 84 percent of taxpayers would see a tax hike and only the wealthiest 16 percent would see a cut?
Meanwhile, according to the ABC/Washington Post survey, which was conducted last week and released today, Rick Perry's flat tax proposal actually is more popular than Cain's 9-9-9 plan with both the public at large and the Republican electorate, particularly with very conservative voters:
As noted, very conservative Americans express a favorable opinion of a flat tax plan by a vast 40-point margin. The same group, by contrast, only divides on 9-9-9, with 46 percent seeing it favorably, 49 percent unfavorably
So now we know why Rick Perry just proposed a flat tax. And it has nothing to do with being more principled than Mitt Romney.