As governor of South Carolina, Mark Sanford has made a mark not by creating any new social programs or by slashing taxes or making some other dramatic gesture. He's done it by doggedly opposing new spending at every opportunity, to the point where he's struck many critics as a monomaniacal economic Luddite.

Sanford's opposition to President Obama's American Recovery and Reinvestment Act, and in particular his insistence on using up to a fourth of his state's stimulus funds to pay down debt or refusing it outright, has fast made him a folk hero to conservatives. To some, Sanford's opposition to the stimulus funds is an act of political grandstanding, a naked effort to sell out the poorest and most vulnerable South Carolinians in order to curry favor with a national Republican audience.

To others, he has struck a mighty and principled blow against big government. Whatever else Sanford has done, he has given conservatives a rare opportunity to return to their roots and to shake off the contradictions and compromises that have built up over the past 30 years.

When Barry Goldwater ran for president in 1964, conservatism was a rigorous and demanding creed. Rather than promise tax cuts, Goldwater insisted on balanced budgets and sound money. After promising to get rid of any number of New Deal social programs, and after pledging to privatize the Tennessee Value Authority and other cherished infrastructure projects, Goldwater didn't promise anything material in return. No manna would fall from the sky in Goldwater's America. He simply argued that shrinking the federal government and reducing its power would encourage self-reliance, and that self-reliance would encourage the virtues of thrift and industry.

It is easy to see why the supply-siders later derided Goldwater's old-fashioned worldview as "root-canal economics," as it promised a lot more pain, at least in the short term. But Goldwaterism had the virtue of coherence and consistency.

In the decades that followed, conservatives moved away from Goldwater's demanding creed, not least in order to win over voters who never fully embraced the politics of self reliance. Whereas in 1976 Ronald Reagan emphasized the central importance of balanced budgets and devolving power from the federal government to the states, in 1980 he veered sharply away from "root-canal economics," promising instead to deliver pain-free prosperity through a sharp reduction in taxes.

At the same time, Reagan backed a massive increase in defense expenditures, a kind of military Keynesianism that helped fuel the Sunbelt boom. Many of Reagan's small-government admirers were growing rich off big government defense contracts.

During the presidency of George W. Bush, this contradiction grew sharper still. Convinced that tax cuts were the elixir the economy needed, the Bush White House never reversed course to raise taxes to reduce the yawning deficit, unlike Reagan and the first President Bush. The Iraq War was to be financed by debt rather than by taxes. It is hardly surprising that many libertarians turned against Bush, as they were convinced, rightly, that war inevitably expands the power of the state. What was surprising is that so few conservatives appreciated that President Bush's tax cuts were in tension with his efforts to make the world safe for democracy.

During the 2008 presidential campaign, virtually all of the major Republican candidates embraced "Bushism"--pro-war, anti-tax, pro-spending. Only Ron Paul, the eccentric Texas congressman, was willing to make a comprehensive case against statism. And though he attracted considerable enthusiasm from a dedicated cadre of young activists, there was no way he could have captured the Republican nomination.

Now, however, Mark Sanford has taken on many of Paul's themes. Unlike John McCain or Mitt Romney, Sanford goes far beyond criticizing earmarks. In the face of a severe recession, he has refused to accept hundreds of millions of dollars in federal aid. Recognizing that the military establishment represents an enormous slice of federal spending, Sanford has also declared that he opposes pre-emptive wars, like the invasion of Iraq. In short, Sanford is the real deal. He is the candidate Rush Limbaugh and countless others who embrace the cause of shrinking government have been waiting for.

But the real test is whether Sanford is willing to put shrinking government ahead of cutting taxes. The evidence suggests that the answer is yes. Earlier on in his tenure as governor, Sanford made a serious effort to gradually eliminate the state income tax. Yet he ultimately came to terms with the fact that he'd have to raise another tax, like the much-despised property tax, to make up for the lost revenue, and so he ultimately abandoned his plan. Rest assured, other Republicans, including George W. Bush, wouldn't have had the same scruples, as evidenced by the state of our public finances.

Though I can't say I agree with every detail of Sanford's vision of limited government, I find him extremely impressive. President Obama has, through the force of his intellect and personality, expanded the scope of political debate in the U.S. He has, in just a few short weeks, moved the center of political gravity to the left. We're now seriously debating an expansion of government that hasn't been on the table since the 1970s.

Mark Sanford represents the counter-reaction. He is moving conservatism away from the delusions of pain-free prosperity and toward the rigor of self reliance. My sense is that this is not a move that will help Republicans win elections. Just as LBJ crushed Goldwater in 1964 by highlighting the many middle-class benefits he put in place, Obama will certainly try to do the same thing to an aggressive budget cutter like Sanford.

Yet this might be the political argument we need. At some point in the near future, we will come to the sudden, sharp realization that we're not as wealthy as we thought we'd be. And while no one wants to balance the budget on the backs of the poor, an evocative phrase that George W. Bush once deployed against congressional Republicans, we might eventually be forced to trim the benefits we provide to middle-class taxpayers, particularly ones provided through the tax system. Sanford seems like the only politician, Republican or Democrat, with the guts to make that case.