Health care reform is one of the most talked about, yet least acted upon, issues on the national political agenda.

From Hillary Clinton’s doomed reform attempt 15 years ago to the current presidential race, the topic has stayed on the front burner.

American people and businesses spend $2 trillion a year on health care. That’s 18 percent of our gross domestic product and twice as much as any other nation.

Yet the United States ranks 45th in life expectancy and its health care system ranks 137th in the world, according to the World Health Organization.

At the heart of the controversy is to what extent the government should involve itself. Advocates for a Canadian or European-style system of universal care run up against cries of socialism and misplaced trust in the bureaucracy. Those who favor leaving care to private enterprise are criticized for ignoring the poor and underserved for the sake of profit.

Here are the proposals from the two leading presidential candidates, Republican John McCain and Democrat Barack Obama.

Obama proposes universal coverage through a combination of federal programs and private enterprise.

“If you already have health insurance, the only thing that will change for you under this plan is the amount of money you will spend on premiums. That will be less,” Obama states on his official Web site. “If you are one of the 45 million Americans who don't have health insurance, you will have it after this plan becomes law.”

Obama estimates implementing his plan would cost around $65 billion, although some experts put it at $100 billion per year or more, as health care costs are likely to continue to rise.

Obama envisions universal coverage by 2012,  including health insurance for children. Employers would be required to offer “meaningful” coverage or contribute a percentage of their payrolls toward federal insurance programs.

 McCain emphasizes the importance of individuals and families taking control of their health care choices.

On his official Web site, he notes that health care reform is a fundamental economic issue, for individuals, employers and the government. “Bringing costs under control is the only way to stop the erosion of affordable health insurance, save Medicare and Medicaid, protect private health benefits for retirees and allow our companies to effectively compete around the world,” he states.

McCain rejects government-sponsored universal coverage. He proposes tax credits of $2,500 for individuals and $5,000 for families to help pay for health insurance, with the government sending money directly to the family’s chosen provider. McCain would also work with governors to develop a model that states could follow to assure high-risk patients have access to health coverage.

The candidates agree on several aspects of health care policy, including efforts to lower drug prices. McCain wants to bring greater competition to drug markets through safe re-importation of drugs and faster introduction of generic drugs. Obama would allow Americans to buy their medicines from other developed countries if the drugs are safe and prices are lower. He said he will also remove legal barriers to the government using its market power to negotiate with drug companies for reduced prices.

Both candidates favor increasing the use of generic drugs in Medicare and Medicaid, with Obama seeking to prohibit big-name drug companies from keeping generics out of markets.

Both favor expanded federal funding for stem cell research and have pushed for “portability,” the ability of a worker to stay with the same health plan even if moving from job to job, taking time off or retiring.

Experts agree both plans are problematic, and are unlikely to fully solve the riddles of escalating prices or lack of access to care.

While McCain says his plan is revenue-neutral, experts note the tax credit plan would be costly. Further, his plan lacks specifics when it comes to expanding care to the uninsured.

Obama’s plan would come with a substantial price tag, the cost of which does not seem adequately covered by touted medical care efficiencies and increases in insurer competition.