Robert McIntyre and Jonathan Crystal's assessment of my tax proposal in "Who, Me? Raise Taxes? What the Candidates Say" {Outlook, Jan. 24} might have been more telling had they not dismissed two-thirds of it. I'm the first to concede that a flat consumption tax would disproportionately burden the poor and middle classes. That's why I've proposed three different ways to offset the burden for those income groups. Here's how it could be done:

Exemptions for basic necessities. Low-income families spend most of their income on necessities such as food, shelter and medicine. Exempting some or all of these from the consumption tax would reduce the effective rate of taxation for those who spend most of their income on necessities.

Income-tax credits for low-income families. Under this option, low-income families would receive a credit on their income-tax liability to make up for the consumption tax.

Direct rebates for low-income families. Although many poor families pay no income tax, they could be sent a direct rebate check. Several economists say this is the most efficient way to make the tax progressive. Those families at or below the poverty level would receive a full rebate; those above the poverty level would receive partial rebates that would decrease with income on a sliding scale.

I am committed to ensuring that the poor pay nothing, middle-income people pay about $1 a day and the wealthiest Americans pay about ten times as much.

There is, of course, a broader issue here. Not one of my opponents in the presidential race has put forward a deficit-reduction plan that is even remotely credible. I am perfectly happy to debate the merits of my proposal, but until anyone else has a real alternative, the question will be not which kind of tax, but which candidate is willing to stand up with any serious answer to our most pressing economic challenge. BRUCE BABBITT Washington