Sanders’s Senate office did not immediately respond to a request for comment. He has introduced a Medicare-for-All bill in Congress that has also been embraced by Senator Elizabeth Warren, one of his rivals.

Sanders has proposed a wealth tax, a bank levy and premiums paid by employers and employees. But that only raises about half of what is needed, meaning that payroll taxes and income tax increases would necessarily have to be part of the plan.

“There are likely to be a lot more losers than winners, ” Brian Riedl, a senior fellow at the right-leaning Manhattan Institute. “It’s hard to do the tax shift without making most families losers.”

Large families with lots of children and older, sicker people with large out-of-pocket costs are likely to fare well under a Medicare-for-All plan, said Marc Goldwein, a senior vice president at the Committee for a Responsible Federal Budget, a think tank.

Many of the 181 million taxpayers with employer-sponsored coverage are likely to see their taxes go higher than their current health care spending, because about 56% of their medical costs are covered by their company, according to the Milliman Medical Index, which tracks annual health care spending.

For example, a person making $50,000 with employer-sponsored coverage spends about $5,250 annually on health care, meaning that under Sanders’s plan, her or his taxes would be nearly double the person’s current health care costs. If that person bought her or his own insurance, it would cost about $10,000, equalizing the $10,000 tax increase.

Those on Medicaid, the government-sponsored insurance program for the poor, are likely to see their tax burdens rise far beyond their current health spending, Riedl said. A family of four earning $30,000 spends about $1,200 annually on health costs, according to the Kaiser Family Foundation estimates.

Sanders’ plan also assumes that health providers will be reimbursed at Medicare rates, about 40% below what they receive from private insurers. Health care experts question whether a cut this large is feasible, meaning that the cost for Medicare for All could be even higher.

“The overarching question is whether it could reduce spending by paying doctors and hospitals less,” Cox said.

Sanders was defensive during last week’s debate when asked if the middle class would pay higher taxes to fund Medicare-for-All. “Yes, they will pay more in taxes, but less in health care for what they get,’’ he replied.