Sanders was in Columbus last week making some of those same points.

“After we defeat this disastrous Republican” health plan, he declared, “our job is to go forward and pass Medicare-for-all single-payer system. If every other major country on earth can do it, surely this country can do it as well.”

Sanders is hardly alone among progressives. The California state senate last month approved a single-payer model while 112 Democrats in the U.S. House have co-sponsored a single-payer plan financed by taxes instead of premiums, out-of-pocket expenses, and co-pays charged by insurance companies and hospitals.

“Most people would be paying less than they are paying now and they would get better health care,” said Gerald Friedman, a professor of economics at the University of Massachusetts at Amherst who helped design the single-payer plan Sanders promoted last year.

“It’s a win-win win except if you’re a drug company or an insurance company or a hospital,” Friedman said.

But Republicans and some analysts don’t see it as a win-win. They cite Sanders’ home state of Vermont, which dropped efforts in 2014 to install a single-payer system after state lawmakers discovered how high they would have to raise taxes.

Critics also note that while the California state senate approved a single-payer plan, the state assembly shelved the idea when the cost was estimated at $200 billion a year.

“Vermont is a highly instructive as a case example because the governor and the legislature were so determined to do it,” said John E. McDonough, a professor of public health practice at the Harvard School of Public Health. “They gave it everything they had and couldn’t make it work.”

Health care around the world

Supporters of single-payer tend to cite the Canadian Medicare system as the ideal, but there are a wide variety of systems where governments play a role in health care.

In Canada, taxes finance about 71 percent of all health costs and all Canadians are covered. A patient does not pay to see a physician, and the doctor bills the province for the fee.

According to the Commonwealth Fund, a foundation in New York City that analyzes health-care systems throughout the world, more than 60 percent of Canadians also buy private insurance to pay for services not covered by the government, such as vision and dental care and prescription drugs.

Great Britain offers a much more socialized system based on taxes financing a comprehensive system of free physician care and public hospitals. “They run the health system like the town of Amherst runs its fire department: It’s paid for and if you need it, you use it,” Friedman said.

Most industrialized nations — such as Canada, Great Britain, Germany and Australia — spend less than 12 percent of gross domestic product on health care, while the United States spends 17 percent, according to the Commonwealth Fund. Other industrialized nations also have longer life expectancy and lower rates of infant mortality than the United States.

During his appearance last weekend before 2,200 people in Columbus, Sanders said he lives “50 miles away from Canada; they manage to provide health care to all their people. Go to Germany, go to the U.K., go to Scandinavia, go to France. Every major country understands that in a civilized society, health care must be a right for all people.”

Yet most Americans have never warmed to a national health insurance system. In a statewide ballot campaign in California in 1994, less than 27 percent of voters supported adoption of a single-payer system. A similar statewide ballot issue in 2002 in Oregon won the support of just 21.5 percent of the voters.

Although Friedman argues Americans would save money by paying taxes instead of health costs, Kenneth Thorpe, chairman of the Department of Health Policy and Management at Emory University in Atlanta, said Friedman is “not even close” to being right.

Last year Thorpe, a former Clinton administration official, calculated that Sanders’ single-payer plan would require the federal government to raise nearly $14 trillion in new revenue during a 10-year-span.

“We would need a Value Added Tax for single-payer; you’re not going to do that through the income tax,” said AEI’s Miller. “This is make-believe land.”

Some results better in U.S.

In determining why America is less healthy than many other countries, the nation’s obesity rate can’t be ignored.

Canada and Great Britain both have obesity rates around 25 percent, or one in four people. Japan is in single digits. Countries like Sweden and Denmark are at 11.7 and 14.2 percent, while the U.S. was 35.3 percent, according to the latest data from the Organization for Economic Cooperation and Development.

The quality of care differs greatly by country, but the American health care system does fare better in some categories.

On sophisticated care, such as cancer treatments, the U.S. system produces substantially better results without the waiting times that plague the Canadian and British systems. The Commonwealth Fund concluded that between 1995 and 2007, cancer mortality rates in the U.S. plummeted at a faster rate than any other major country.

“I think if you look at the countries that spend less than us and have better outcomes there are two reasons,” said Thorpe. “One is they have a better primary care system …And second they integrate better and spend more on social services, housing and things like that.

“At the specialty level we do very well on different types of cancer and cancer treatments and mortality rates.”

Marion Renault of the Columbus Dispatch contributed to this story.