In previous articles, we have compared the three remaining presidential candidates' positions on dealing with the uninsured, containing drug and other costs and Medicare, Medicaid and other federal entitlements. This final piece highlights the main ways the candidates' plans differ, as well as the ideas that are unique to each plan.

Senator McCain's position on covering the uninsured is the most significant difference among all three plans. Simply put, McCain does not have a position on the uninsured. In fact, McCain does not seem to agree that universal health care coverage is an important goal; he opposes any form of government mandate requiring such coverage. What McCain does propose is a combination of regulatory disengagement by the government and cost savings through free-market competition. "We can improve health and spend less," McCain says, "while promoting competition on the cost and quality of care, taking better care of our citizens with chronic illness, and promoting prevention that will keep millions of others from ever developing deadly and debilitating disease."

Critics point out, however, that we already have one form of quite vigorous competition in the health care marketplace — competition by insurers to "cherry pick" the young and healthy while avoiding any responsibility for the old and sick. As Elizabeth Edwards has pointed out, because of their respective pre-existing conditions, neither she nor Senator McCain would be able to buy health coverage under McCain's plan. New York Times columnist Paul Krugman says that McCain's health care reform plan is based on the "foolish claim, refuted by all available evidence, that the magic of the marketplace can produce cheap health care for everyone." Even if the competition McCain envisions were to reduce health care costs, Krugman argues, "the idea that it could cut costs enough to make insurance affordable for Americans with a history of cancer or other major diseases is sheer fantasy."

The Obama and Clinton health care plans propose to insure everybody — or almost everybody — in America. Critics fault them for not being entirely honest about how much this will cost and how they will pay for it. Few serious observers believe that "rolling back the Bush tax cuts," managing chronic diseases, or instituting an electronic patient records system would produce enough savings to cover the cost of universal care.

McCain is the only candidate who is proposing changing tax law to discourage employer-provided health benefits and replacing this with a tax credit which individuals and families could use to help pay for private insurance.

Unique to Senator Clinton is her position requiring coverage for every man, woman and child in the U.S.. Americans who pay for their own coverage, rather than receiving coverage through their employers, will receive help from the federal government in the form of a tax credit, and insurance companies will not be allowed to turn away would-be customers because of a pre-existing illness. All plans will be "portable," meaning that people could take their insurance with them from job to job or from work through a period of unemployment, without any loss of coverage.

Senator Obama claims that his plan — which mandates universal coverage for all children — would cover almost everyone. He criticizes the Clinton plan as too rigid and expensive. "Sen. Clinton's idea is that we should force everyone to buy insurance," Obama said in a statement released to CNN, "She's not being straight with the American people because she refuses to tell us how much she would fine people if they couldn't afford insurance."

What all three candidates' health care proposals have in common their lack of specifics. This is certainly no accident. The problem is that while most Americans rank health care reform, along with the war in Iraq, as one of their key election issues, there is widespread disagreement over what needs reforming and how.

Health care "could well be the critical issue in this election," says Robert Blendon, professor of health policy and political analysis at Harvard University's School of Public Health. "The dilemma for the candidates is how they can talk about it in a way that will differentiate themselves from one another without getting into specifics that will turn voters off."

"The thing that is critical to understand is that the middle class may be dissatisfied but most of them have employer insurance, so they have something to lose," says Blendon, who talks regularly with candidates about health care reform. "They are not prepared for a national experiment that will threaten what they have."