Young Americans are sending a clear signal to congressional leaders eager to devise a prescription drug plan for the elderly: Such a benefit should be included in Medicare, but only if it is limited to the low-income aged.

President Bush just proposed a 10-year, $ 153 billion program to fund a prescription drug program for the elderly and disabled. This funding request falls dramatically short of the $ 400 billion that many congressional budget experts say is needed to provide drug coverage for all elderly Americans who lack it in an environment of skyrocketing pharmaceutical prices. But wait.

Even without the added costs of any prescription drug program, Medicare will start running deficits before today's 30-year-olds reach retirement age. Experts now predict an astounding cumulative shortfall of $ 333 trillion over the next 75 years (in non-inflation-adjusted dollars).

That's one third of a quadrillion dollars! On its current course, by 2075, Medicare will consume more than 8 percent of gross domestic product, nearly four times more than today. That number may not seem relevant to many older adults, but to the baby boomers' children and grandchildren, it will be.

There are good reasons to consider a new prescription drug benefit. Many seniors need -- but cannot afford -- necessary medications. But keep in mind, two thirds of all seniors already have some form of prescription drug coverage, either through employer-sponsored plans, supplemental insurance or HMOs. A new benefit needn't include most of those already covered.

Furthermore, this issue should be examined in the context of the entire Medicare program. To expand Medicare without acknowledging tomorrow's costs or structural problems will only exacerbate the looming financing crisis. An overly generous new prescription drug benefit easily could swallow -- like a bottle of pills -- all of Medicare's short-term surpluses.

More important, once those surpluses are gone, there will be no way to fund the expensive new drug benefit, and this will further jeopardize the core Medicare program.

Consider how younger generations think specifically about launching a new prescription drug benefit.

A national survey of 500 young adults aged 18 to 34 -- just released by Third Millennium and conducted by the bipartisan polling team of Democrat Jeffrey Pollock and Republican Frank Luntz -- found that young adults clearly support a prescription drug benefit for seniors, but that level of support drops dramatically as the would-be recipient's income increases.

More than four out of five young adults would support a prescription drug benefit in Medicare for seniors with household incomes of $ 20,000 or less. Three out of five would support a prescription drug benefit in Medicare for seniors with household incomes of $ 40,000. Above that $ 40,000 level, though, support plunges. Only one third would give this benefit to seniors with household incomes of $ 60,000, and a mere one out of five would support it for those with incomes of $ 100,000.

Young adults don't want Uncle Sam to stock the medicine chests of wealthy seniors.

Our generation's message to Congress is clear: We cannot afford or support a massive new entitlement for those who don't need it.

Indeed, is it fair to ask low-wage workers, who themselves barely can afford prescription drugs or health insurance, to subsidize the drug benefits of those who want an unneeded handout?

Ignoring foreseeable Medicare shortfalls will add to young people's cynicism about government and whether the programs they subsidize today will be available to them tomorrow. Remarkably, our survey of 18-to-34-year-olds found that nearly half (43 percent) of people in that category think that the TV soap opera "General Hospital" will outlast the Medicare system. When a program is facing a long-term financing shortfall, expanding benefits is not reform.

There are many options -- raising the eligibility age, charging affluence-testing premiums, relying more on managed care for seniors, and boosting national savings -- that will help keep Medicare in balance. We should also expand Medical Savings Accounts so younger workers can pre-fund their medical expenses.

Providing health care to seniors and modernizing Medicare should not be a battle between young and old. It should instead be a discussion about who among us -- of all ages -- should receive benefits, and who among us -- of all ages -- funds them.

Accordingly, when it comes to prescription drugs, we must target new benefits only to those who cannot afford coverage on their own. And we must spread those costs among those -- of all ages -- who can afford them.