Looking at the sponsors is interesting. The main sponsor, Mike Enzi, is a conservative Republican, who you might not normally expect to be sponsoring tax bills. But he represents Wyoming, a state that heavily depends on sales taxes, because they've made the decision not to tax personal or corporate income, leaving sales/use taxes as one of the major revenue sources (responsible for ~40% [1] of the state budget).

[1] See the pie chart on pg. 4 here: http://eadiv.state.wy.us/s&utax/Report_FY11.pdf

Its not too unusual for a republican to be in favor of a sales tax. Income, capital gains, property, and inheritance taxes are another story.

hey thanks