Buried amid the barrage of statistics hurled about on the Democratic presidential campaign trail this year is a puzzle. Vice President Gore claims his health care plan would lead to nearly 90 percent of Americans gaining insurance coverage, at a cost of about $25 billion annually. Bill Bradley claims his plan would lead to 95 percent coverage, at a cost of about $65 billion.

Why should it cost Bradley $40 billion a year to cover just an extra 5 percent of Americans?

The answer is that his plan would give a new benefit not just to the uninsured, but also to millions who have health insurance.

That fact, as Bradley's health advisers see it, is one of the most compelling features of his plan. From Gore's vantage point, it is a critical flaw. In either event, the contrast has become a major issue between the two candidates and underscores a philosophical split about the direction in which progressive government should steer in a post-Clinton era.

Bradley would have the federal government embrace an expensive new responsibility: an entitlement to subsidized health insurance for many Americans, with the largest subsidies directed to the poorest people. After years when Democrats have been on the political defensive and scaled back their ambitions accordingly, his plan reflects a striking revival of confidence in activist national government.

Gore, with a philosophy that advisers say reflects both the successes and failures of the Clinton administration, has concluded that incrementalism and patchwork problem-solving are more politically and financially realistic--and ultimately produce more progressive policies.

"Gore is looking for the next step that we can reasonably accomplish; Bradley is saying I want a guarantee [of coverage] in this country," said Judy Feder, an administrator at Georgetown University and former Clinton administration health official. Feder said she has questions about some of the practical consequences of Bradley's plan.

Neutral observers call it a surprisingly substantive debate on a topic that, after the failure of the Clinton health care proposal five years ago, many assumed would be politically untouchable for years.

"Coverage of the uninsured is back on the political agenda, long before any observer of the 1994 fiasco would have predicted," said Robert Reischauer, a budget and health care expert at the Brookings Institution.

But the serious nature of the debate is obscured by a daily firefight over details. In exchanges that have become increasingly snappish, Gore says Bradley's plan would "destroy" the Medicaid program for the poor and bust the federal budget by spending billions of dollars on subsidies for people who do not need them. Bradley has accused Gore of intentionally distorting the details of his plan and of trying to scare voters in demagogic style. Bradley says Gore has sacrificed the traditional Democratic goal of universal coverage by presenting a "timid" proposal that would only "tinker around the edges."

Reischauer, who headed the Congressional Budget Office during the debate on the Clinton plan, said Gore's critique has "raised the right issues" about Bradley's plan, but in a way that exaggerates legitimate concerns into "crisis-level" problems.

The principal philosophical difference between Bradley and Gore concerns the federal government's system for providing coverage: Can its flaws be fixed, or should a new system be devised?

Bradley, unlike Gore, has chosen the latter--and thus invited criticism that his plan is too costly or unworkable. He would end the joint federal-state Medicaid program, which pays medical expenses for some of the poor. Medicaid, Bradley argues, segregates and stigmatizes the poor, and its eligibility rules vary illogically from state to state, leaving many people uncovered.

In place of Medicaid, Bradley would give the poor refundable tax credits with which to purchase health insurance. All parents would be required to obtain health insurance for their children. And all people would be eligible to buy one of the insurance packages offered by the Federal Employees Health Benefit Program, the plan used by government workers.

The subsidy would hinge on income level. The poorest people--for instance, a family of four making less than $16,700 a year--would get an annual tax credit worth an average of $1,200 for children and $1,800 for adults. The subsidy would gradually decline as income levels rise--and fade out entirely at 300 percent of the poverty level, or roughly $50,000 for a family of four.

Bradley would extend this benefit even to those who buy their own insurance or get it through their employer. The logic, say Bradley advisers, is one of fairness. Lower-income people who have insurance are either spending their own money, or being paid lower salaries if their employer provides the benefit. These people, the argument goes, are as deserving of federal help as those without insurance.

Under Bradley's plan, even well-to-do Americans who purchase their own insurance could receive a tax deduction--a point that has come in for particular criticism from Gore's camp. (Many conservatives support this idea.) The argument made by Bradley is again one of fairness: The insurance that most people get through their employer is not treated as taxable income, so self-insured people should also get a tax-favored benefit.

"Bradley stands squarely in the tradition of Democratic nominees going back to Franklin D. Roosevelt, that access to health care is one of those basic rights," said Tom Higgins, an Oregon health care expert who is advising Bradley's campaign. "The Bradley approach is 'I'm going for fundamental, structural reform.' "

But Bradley does not accept some of the more far-reaching proposals of some Democrats, such as the idea that government should impose a "single-payer" system covering all people equally. And, like many Republicans, he wants to use the tax code to influence individual behavior.

The Gore approach is to seek to improve the existing structure. And he wants to direct new federal money toward expanding insurance coverage for children.

Gore's preferred vehicle is a federal-state program known as the Children's Health Insurance Program (CHIP). He would expand eligibility for children in families up to 250 percent of the poverty level (or to about $41,000 for a family of four). He would allow uninsured parents of these children to enroll. And families with incomes exceeding 250 percent of the poverty level would be allowed to purchase insurance for children through Medicaid or CHIP.

CHIP, according to health care experts, has proven partially disappointing because many eligible families do not enroll their children. But Gore proposes a carrot-and-stick program to prod states into ensuring better participation rates among eligible people. He also proposes other measures to reach the uninsured, including 25 percent tax credits to partially offset premium costs for some small businesses and individuals.

Gore aides acknowledge this incremental approach cannot entirely solve the problem of the uninsured. But they say it can markedly reduce the problem and is attainable--even as he perseveres toward universal coverage.

Administration officials who helped craft Gore's plan say this piecemeal approach was born out of two realities: the searing defeat of the Clinton plan in 1994 and the struggle they have confronted for years in accommodating social spending without violating balanced-budget goals.

Bradley aides say their plan, too, was influenced by the failure of the Clinton plan. While expanding government's role in paying for coverage, they avoid the employer mandates and extensive administrative apparatus that were central to Clinton's plan.

Yet these cautions have scarcely limited the attacks that Bradley's plan has received, not just from Gore but from some independent analysts. The criticisms follow two themes, which at first blush seem contradictory--that Bradley's plan would not cover as many people as he says it would, and that it would cost more than he says it would.

Kenneth Thorpe, a former Clinton administration official now at Emory University, concluded that Bradley's plan would cost about $80 billion in the first year, and more than $1 trillion over 10 years. That would essentially use up all of the projected federal surplus outside the Social Security program--money Gore says should be dedicated in part to Social Security, education and other needs. Gore's total health plan, according to Thorpe, would have a 10-year cost of about $312 billion.

The main reason that Bradley's plan would cost more than the campaign projects, Thorpe said, is the likely cost of a relatively generous new benefit to give seniors prescription drugs under Medicare. Gore proposes a more limited drug benefit.

The other place Bradley's plan falls short, Thorpe said, is in reaching the uninsured. An $1,800 subsidy is not enough to purchase even a minimum health care plan in most cases, he said. Most of the plans sold under the Federal Employees Health Benefit Plan cost more than $1,800. Bradley, he said, would either have to raise the figure, or confront the reality that many people will remain uninsured if they receive only a partial subsidy.

Just under 84 percent of Americans have health insurance, leaving 44 million uncovered. Thorpe said Bradley's plan, rather than boosting this to 95 percent, would reach only 89 percent; he said Gore's proposal could lead to 88 percent coverage. Bradley's camp disputes these figures, and has accused Thorpe of bias. Last week, the Bradley campaign unveiled a report from academic supporters saying that Bradley's plan would expand coverage by 30 million people, while Gore's would reach only 7 million of the uninsured.

Other health experts, such as Reischauer, say there is a spurious precision to much of the debate, because predicting coverage rates is guesswork. But they say Bradley is forcing the electorate to confront basic questions--even if the answers are controversial.

"What Bradley is doing is taking a position of, 'What do we want our health care system to look like?'" said Gail Wilensky, a senior health care official in the Bush administration. Even so, she predicted, "He's seriously misjudged the willingness of the American people to spend new money."

Competing Health Plans

Bradley plan highlights

* Abolish Medicaid. Instead, poor people would get assistance in the form of tax subsidies, to be used to purchase health insurance.

* Allow Americans to buy plans through the Federal Employees Health Benefit Program. Most Medicaid recipients would be funneled into this program.

* Allow all people, regardless of income, to deduct the cost of their health premiums if they are buying individual policies.

* Uncapped prescription drugs benefit under Medicare.

The candidate's claims:

Bill Bradley argues that Medicaid segregates the poor in an often ineffective program. Eligibility rules vary from state to state, and many needy people are not eligible. He says his program of subsidies will allow the needy to be mainstreamed in a program that is equal to the generally well-regarded health coverage extended to federal workers.

What critics say:

Bradley puts the cost of own plan at $65 billion annually; some outside experts say it would be more than that, particularly if Bradley aims to reach his goal of insuring 95 percent of the population. Vice President Gore has said it is reckless to dismantle Medicaid with a system of tax credits that might not be generous enough to provide equivalent coverage.

Gore plan highlights

* Extend eligibility in the Children's Health Insurance Program (CHIP) and allow uninsured children above the eligibility cutoff to buy into Medicaid or CHIP.

* Allow uninsured people ages 55 to 65 to buy into Medicare.

* Tax credits for 25 percent of premiums for individuals buying their own insurance, or for small businesses joining purchasing coalitions.

* Prescription drug coverage under Medicare, capped at $5,000.

The candidate's claims:

Gore says his plan can address the most pressing need -- covering uninsured children -- with an annual cost of about $25 billion that will still leave the government enough money to address other needs, such as aid for education or extending the solvency of the Medicare and Social Security programs.

What critics say:

Bradley has said Gore is merely tinkering around the edges of a problem that needs systemic solutions. The CHIP program, run jointly with states, has had trouble getting those who are eligible to enroll. Medicaid rules vary widely among states, leaving many needy people uncovered.