Democratic presidential candidate Bill Bradley outlined a plan today intended to provide all Americans access to health coverage by significantly expanding federal subsidies and tax credits to help families buy insurance.

Bradley's proposal, aimed at the roughly 45 million people who lack health coverage, would pay all or part of the insurance premiums for nearly 30 million lower-income children and adults. It also would for the first time allow anyone to buy private coverage through the program that insures federal workers.

The plan, which Bradley said could cost as much as $65 billion a year, represents one of the most ambitious government initiatives offered so far by a presidential candidate of either party. It also elevates the question of how to help the nation's uninsured to the front ranks of campaign issues, and puts the former New Jersey senator into a direct competition on the topic with Vice President Gore, his rival for the Democratic nomination, who released his own health care proposal three weeks ago.

Gore promised to guarantee access to health insurance to all children and their parents in low-income families. But his plan would focus exclusively on people who currently lack coverage. It also would bring about less change to existing public health programs for children and the poor.

By addressing the problem of the uninsured, the two Democratic candidates have chosen as a significant theme of their campaigns an issue that is enormously popular with Democratic voters -- but that has proven to be politically perilous, depending on how it is approached.

In his speech today, Bradley argued forcefully that the federal government must assume responsibility for making health care coverage affordable to virtually everyone. "We can commit ourselves to the proposition that when it comes to health care, everyone will have the American dream -- at last," he said.

But after the defeat of the Clinton administration's plan for universal coverage in 1994, Bradley appears to have avoided certain expansions of the federal role in health care, several health policy analysts said today. "He's obviously trying to straddle the delicate road between [providing universal insurance] without having to come with the heavy hand of government and mandating all this stuff," said Ewe Reinhardt, a Princeton University health economist.

Unlike the Clinton proposal, which would have created a government system to mandate universal coverage, Bradley is proposing that only children be required to have insurance. His plan would retain the principle of employer-sponsored health insurance, which covers the bulk of Americans. And while creating subsidies, his plan also would rely on tax credits and a broader role for the insurance program for federal employees -- ideas that have been favored by many Republicans in the past.

Bradley's proposal also would expand coverage through the Medicare program by helping elderly Americans pay for prescription drugs. And his plan would effectively eliminate Medicaid and the new Children's Health Insurance Program, replacing them with a new approach that would shift responsibility from states to the federal government and would give participants greater access to private health plans.

Bradley said he would pay for the proposal with the part of the projected federal budget surpluses that is not generated by Social Security taxes, and also by savings from some cost-containment measures.

Gore advisers attacked the Bradley proposal for failing to set aside any of the projected surpluses to shore up the long-term solvency of Medicare, which they said Gore would do. "It is a fundamental flaw," said Elaine Kamarck, a senior policy adviser to the Gore campaign. "It does not protect Medicare."

The Gore camp also said Bradley's plan could result in the creation of a new federal bureaucracy, raise premiums for the federal employees health care system, and result in already insured workers shifting to the federal plan.

But Bradley dismissed the criticisms, saying the Medicare issue could be addressed in the near future without significantly endangering the system's financial health. Bradley also belittled Gore's health care proposal as "definitely timid" in comparison to his own and said there is no better example of the "fundamental differences" between his campaign and Gore's than their approaches to health care.

Bradley issued his plan as the race for the Democratic nomination has begun to intensify, with Bradley running roughly even with Gore in such early primary states as New Hampshire and New York.

In his proposal, Bradley seeks to move the country toward coverage of about 95 percent of all Americans -- if everyone takes advantage of the provisions he outlined today. The plan also provides more details on how he would pay for those provisions than Gore's does. The states, under Bradley's approach, would be responsible for the growing problem of long-term care. Bradley advisers said that, on balance, the states would gain $18 billion in the transaction.

Bradley envisions a health care system that would treat children, working adults and the elderly in somewhat different ways. In requiring children to have health coverage, it would let parents insure them under an existing plan or by buying into the federal system if their children are not covered. But it provides no enforcement mechanism or penalties for parents who do not provide coverage for their children. Bradley said he would "trust in the basic goodness of the American people" to insure their children.

Bradley would provide a sliding scale of subsidies for children in families that earn up to 300 percent of the poverty level, or about $49,200. About 84 percent of the 11 million uncovered children would receive a full or partial subsidy, a refundable tax credit of up to $1,200. Families above $49,200 would be required to buy their children's insurance but would receive a tax break to help offset some of the cost.

All adults would have two options. They could continue to participate in an employer plan or buy into the federal program. Adults with incomes below $16,400 would receive a $1,800 tax credit, payable in advance to the insurer, and those earning between $16,400 and $32,800 would receive a partial credit. All would be able to exclude premium payments when calculating their income for tax purposes.

For Medicare patients, Bradley's plan would offer a prescription drug benefit with a $500 deductible, a $25 monthly premium and a 25 percent copayment. He also proposed that Medicare begin to pay for more services, such as housekeeping and transportation, to help elderly people remain at home rather than go into nursing homes.

Goldstein reported from Washington.