Last week Vice President Al Gore not only reaffirmed his support for the Clinton Administration's USA (Universal Savings Account) proposal for encouraging private retirement savings, but improved on it: calling for a 3-to-1 public match for private savings by low-income families; a 1-1 match for middle-class families; and a 1-3 match for higher earners.

This "Social Security Plus" proposal addresses one of the most important problems facing our retirement system: the meager private savings of low-income Americans and their dangerous dependence on Social Security alone for retirement income. By designing his proposal as a tax cut (the government match for private savings would be in the form of a tax credit), Gore has strengthened his case that he favors progressive tax cuts focused on savings and investment, while Gov. George W. Bush promotes tax cuts that would boost consumption by high earners.

The Gore proposal also changes the dynamics of the Social Security debate in the presidential campaign. Both candidates now favor steps to encourage private retirement savings accounts, that will strengthen one of the three "legs" (the other two are Social Security and private pensions) of retirement security while giving low-income Americans a shot at wealth-creating assets. Gore would use general revenues; Bush would use a "carveout" of a portion of Social Security payroll taxes.

Neither candidate, unfortunately, is talking about the broader issue of Social Security reform--structural changes that would keep the system solvent without gobbling up an ever-higher share of national wealth at the expense of wage earners and badly needed investments in future generations. Gore has proposed an expansion of benefits for widows and stay-at-home moms, while arguing that future budget surpluses make it unnecessary to reduce benefits in other areas. Bush has vaguely endorsed the idea of structural reform as something that Republicans and Democrats should undertake in the future, but does not have, nor seem inclined to develop, his own plan for doing so.

We now have a different and more constructive debate on retirement security than the old "third rail" politics of attacking anyone who dared suggest any change in the sacred edifice of Social Security. But in the long run we need a much broader debate about the fairness and fiscal sustainability of Social Security in which no subject, including benefits, is off the table.