Let's put aside, for now, the question of whether state government can afford to devote some of its meager tax base to Gov. Mark Sanford's coveted state-income-tax cut. More pressing in the near term is another question: Why he would advocate a state tax base reduction that gives wealthier state taxpayers proportionally larger tax breaks than the breaks accorded to lower-income residents.

The question is pertinent not only because a subcommittee of the S.C. House Ways and Means committee last week approved Sanford's proposal, which failed last year in the S.C. Senate. Also last week, the House upheld Sanford's recent veto of the 2004 bill that would have capped property-tax increases on high-end residential property, thereby shifting the property-tax burden to all other classes of taxable-property owners.

The governor clearly understands that ability to pay is the bedrock principle of any fair state-taxation plan. If he didn't get it on ability to pay, he would have allowed the property-tax cap to become law. Yet the equally pernicious income-tax cut, first proposed during his 2002 campaign for governor, remains his top legislative priority.

His plan, readers will recall, would phase down the state's top marginal income-tax rate from the current 7 percent to 4.75 percent, in years when the state runs a surplus. But the Sanford plan does not address the S.C. income tax's greatest travesty - that the state applies its highest marginal rate to South Carolinians with taxable income greater than $12,650. That's only $160 above the current federal poverty line for a two-person household.

It's no surprise, then, that according to the S.C. Board of Economic Advisers, 25 percent of the savings from the Sanford plan would go to the wealthiest 1.7 percent of South Carolinians - those making more than $200,000 a year. A family of four at the poverty line, $18,850, in grim contrast, would get a tax break of $139.50 - while still paying 294.50 in state income tax.

The Republican argument in support of such tax-break regressivism: If the state gives wealthier South Carolinians the biggest tax breaks, they, in turn, would reinvest it in the state's economy, lifting wealth levels for everyone in time.

Maybe, maybe not. Regardless, we have no problem with letting friends and neighbors who are more successful keep more of their discretionary income.

But why won't Sanford and legislative Republicans also consider significantly reducing - or eliminating - the income-tax burden for poor South Carolinians? That proverbial S.C. family of four at the poverty line could buy a lot of groceries or clothes for the kids with the $434 per year that the state takes from them now, at the 7 percent tax rate.

The dirty little secret behind the Sanford income-tax-cut: Exempting poor families in this fashion while also putting megabucks back into the pockets of the prosperous would give away too much of the S.C. tax base. When you tap poor families for a few hundred here, a few hundred there, pretty soon you're talking real money. South Carolina has many, many poor families.

As written, this plan is unfair, even cruel. The Ways and Means Committee, which takes up the matter this week, should revise it to give poor families significant state-income-tax relief - or refuse to pass it.