Ponnuru notes that "supply-side boldness clearly isn’t paying the political dividends its advocates say it should":
[I]n this campaign, the keepers of the supply-side faith are grim. So far the two Republican candidates who have departed the most from supply-side doctrine have done the best. … The deficit may have finally gotten so large, and our long-term fiscal outlook so bleak, that even Republican voters are less enthusiastic about massive tax cuts that come without matching spending reductions (as in the Santorum, Gingrich, Perry and Pawlenty plans). And the proportion of voters who pay the income tax has fallen a lot since the start of the tax revolt in the late 1970s, so tax plans centered on cutting income-tax rates have less appeal.
The Dish 