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Although a raucous debate over national security has dominated the presidential campaign, President Bush (search) and Democratic rival John Kerry (search) differ even more sharply on how to provide better health care to more Americans.

Kerry's proposal dwarfs that of the president, costing hundreds of billions of dollars more and covering millions more people, according to most independent and campaign estimates.

"They couldn't be more different. It's a very clear choice," said Linda Bergthold, a Los Angeles-based consultant on employer-provided health insurance for Watson Wyatt Worldwide.

The Democrat's plan seeks to stabilize the private, employer-based insurance market that covers more than 150 million people, while expanding government health care programs for children and the poor. The ranks of the uninsured, currently 45 million, would drop to 27 million people over 10 years, according to a range of estimates.

But it would be costly. The campaign says the plan would cost taxpayers $653 billion over 10 years. Other estimates put the cost at double that or more.

Republicans from the president on down have attacked the plan as — in the words of Senate Majority Leader Bill Frist (search) — a "prescription for more government-controlled health care" that would be paid for by raising taxes. Kerry says he would pay for it by rolling back tax cuts for people with incomes of more than $200,000 a year.

Bush would rely on tax incentives and market-based choices for individuals in a plan the White House says would extend coverage to 11 million, and perhaps as many as 17 million, people at a cost of $100 billion to $150 billion. Independent estimates from the conservative American Enterprise Institute and the Lewin Group say the number of newly insured would be more in the range of 7 million to 8 million.

Democrats say the president has done little in the past four years to improve health care and proposes the same in a second term.

"George Bush's health care plan for the past four years has been, 'Pray you don't get sick,"' says vice presidential nominee John Edwards.

Republicans say Democratic attacks ignore last year's Medicare prescription drug law and don't take account of proposals that would bring down costs by giving individuals more control over health care spending.

Two major issues drive both proposals: The 45 million people who lack health insurance is 5 million more than four years ago. And, the percentage of people with insurance through their employer has declined from nearly 68 percent of the population to 63 percent over the same period.

For those who are insured, premiums, deductibles and co-payments have been rising, far faster than overall inflation or wages.

Economists say neither proposal would do much to rein in health care costs, although both campaigns say features of their plans would help.

For Bush, capping medical malpractice awards would lead to fewer meritless lawsuits, a drop in malpractice insurance premiums and substantial cost savings.

Kerry says coordinating care for people with chronic illnesses would bring hundreds of billions of dollars in savings. He also would derive some savings from malpractice reform and permit prescription medicines to be brought in from Canada, a step he says would keep drug prices in check.

Among the components of the Kerry proposal:

—The federal government would pick up most of the tab for workers who incur the highest medical bills, which the Kerry campaign says would allow employers to cut the annual cost of premiums for a family by about $1,000, on average. Employers would be required to offer health insurance to all workers.

—Nearly all children and more working adults with low incomes would be eligible for government health insurance that is paid jointly by Washington and the states. The federal government would pick up a substantial share of state costs.

—Small businesses and individuals between jobs as well as people 50 to 64 years old would receive tax breaks to help them buy insurance coverage.

Major elements of the Bush plan include:

—Tax breaks to individuals with low incomes who buy their own insurance policies and for those who purchase high-deductible policies and have health savings accounts, tax-free investments that can be used for health expenses.

—Association Health Plans to allow small businesses in different states to band together to offer insurance to workers.

—Stepped-up effort to enroll children who already are eligible for government-paid health care.

Health care would seem to offer a natural campaign advantage to Kerry's more ambitious plan, and indeed, a recent Time magazine poll showed he has an edge with voters.

"It's really about economic insecurity. People can't pay their bills. Benefits are not keeping up with their income and they're nervous," Harvard public health professor Robert Blendon said.

So far, the issue has been on the periphery of a campaign that has been dominated by Iraq and terrorism. If the race remains tight, Democrats probably will turn increasingly to health care to sway voters in swing states, Blendon predicted.