There is a solid economic case for moving away from the taxation of income and toward the taxation of consumption. But it is not at all clear to me that a value added tax is superior to other types of consumption tax. I wrote about one alternative a few months back:

It is possible to smooth the jagged edges of the VAT. The late David Bradford, an economist at Princeton University, proposed a variant called the X tax. The difference is that under the X tax businesses would be able to deduct wages and workers would pay taxes on their wage income. The wage tax could be made as progressive as Congress wants, making the X tax more attractive to liberals. It would also be more visible to voters, making it more attractive to conservatives. And wages wouldn’t have to fall.

Whether or not it makes sense to try to reach a grand bipartisan bargain that raises taxes and cuts spending, I think for conservatives to open the debate by talking up specific tax increases–with no talk of what specific spending cuts a deal should include from liberals–is a bad negotiating posture.