I don't agree with everything in this paper, but it's the best case against a VAT that I have seen to date.
…the tax is not a good fit for the United States. It taxes a base that has traditionally belonged to state governments, its introduction would bring with it intergenerational inequities, it has a cumbersome administrative structure that would impose large compliance and administrative costs, and it would slow economic growth. Because of slower economic growth, tax revenues from existing tax bases will fall if a VAT is introduced.
If you're wondering, as an alternative he favors a mix of spending cuts and, if needed, increases in the income tax.