Can we include corporations in the flat tax? Capital gains? Income from shares and investments? If we did that, closed every loophole, had a per-person and per child deduction at some actually sane poverty rate percentage that was tied to inflation, maybe, maybe, maybe I'd be in favor. But honestly without seeing a workout of the numbers, I'm pretty sure I have to say no.
IL does all that, and even gets high marks for the ability of its flat income tax to weather a recession (it's the only part of finances that can, the rest is pretty bad). Yet the Dems are campaigning on a constitutional amendment to shift to a graduated tax using brackets like CA or MN, but without the itemized deductions targeted for the middle class.