Credit has to go to conservative Bruce Bartlett who writes in his National Review column:
There is no indication of what tax rate Speaker Hastert thinks would be necessary to replace all federal revenue. A current proposal by Rep. John Linder (R., Ga.) says that a 23 percent rate would be adequate. But such a low rate can only be sustained by making completely absurd assumptions about what would be taxed. Every serious economist who has ever looked at this question has concluded that a vastly higher rate would in fact be needed.
Of course, President Bush has said:
You know, I’m not exactly sure how big the national sales tax is going to have to be, but it’s the kind of interesting idea that we ought to explore seriously.
I guess taking seriously and not knowing what the tax rate would be is par for the course with George W. Bush.