This beats Mr. Romney, who refuses to propose a cut in individual tax rates lest he be accused of favoring the rich. Mr. Santorum doesn't dodge the class-war argument, which Mr. Obama won't let the GOP nominee dodge in any event. Mr. Santorum was especially effective in Saturday night's debate in making the case that Republicans shouldn't stoop to the Democratic rhetoric of pitting "the middle class" against other Americans. On the other hand, Jon Huntsman's tax reform is superior because it proposes a lower top rate of 23%, which he'd make possible by stripping out nearly all current deductions. Newt Gingrich proposes a voluntary plan with a 15% top rate. Mr. Santorum wants to eliminate deductions for business and the wealthy, but he'd retain some of the costliest deductions, including those for mortgage interest, charities, health care and retirement savings. A President might have to give away these deductions to get a reform through Congress, but Mr. Santorum has conceded them before the bargaining begins.
Overall, we'd score Mr. Santorum's economic agenda as bolder than Mr. Romney's, if not as ambitious as those of Messrs. Huntsman and Gingrich. Judging by this weekend's debates, his elevation to a serious contender has improved the quality of the GOP's economic debate. If Mr. Santorum is going to trump Mr. Romney's money and organization, his best opening is to become the candidate of economic growth.