A skeptical National Review gives Rick Perry's tax plan an unenthusiastic review, writing that its purpose seems to be to "enable Perry to say that his proposal is a 'flat tax'
while also avoiding one of the political disadvantages of the flat tax: the fact that most versions of it would increase tax payments for many millions of people":
No detailed analysis of how much revenue the plan would raise has been done, but it seems highly likely that the number would be much lower than under the current system, and lower than Perry’s team is claiming. Governor Perry has already had to put an optimistic gloss on his proposed spending cuts to get his numbers to balance. If his revenue estimates are also too optimistic then the net effect of his proposals will be to make our already precarious budgetary position worse …
He has chosen to avoid the political liabilities of a flat tax by forgoing its distinctive advantages of simplicity and low compliance costs. The hybrid tax system he would create would in no important sense be flat, and Perry seems unwilling to spell out the cuts necessary to get spending in rough balance with the amount of revenue it would collect. Republicans should try for something better.
But the National Review argument reveals what may the best pushback on Perry's plan, for his GOP primary opponents. Herman Cain's "9-9-9" plan had an obvious weakness: the 9 percent federal sales tax. Perry's plan doesn't appear to have an individual component as politically toxic as that, so the strongest argument against it is probably that it just wouldn't work.