Economic class is not a protected class like sex or race. Otherwise it would make income tax brackets unconstitutional. That said, the income tax should progressively be cut and abolished and replaced with a National Sales Tax
As far as I'm concerned, a "progressive income tax" IS un-Constitutional, as it merely penalizes success with no more reason than "they can afford it" as the excuse. If you don't pay ANY income tax, IMHO, you don't have anything to say in elections, either, as you will surely just vote for those who would give you something at the expense of others....
THAT is how we wound up with the Kenyan Messiah.