Sen. Bernie Sanders' "Medicare for All" plan unveiled last week is an ambitious and (to many) enticing idea: a single, government-run health plan with generous benefits for everyone — just like most industrialized countries have enjoyed for decades.

If only it were feasible in today's United States.

Alas, Sanders' proposal is a pony without a price tag. The Vermont senator has offered only vague estimates of what his plan would cost and a generic menu of tax increases to pay for it. But the biggest problem is politics. As they say in New England, you can't get there from here.

His proposal, which would eliminate almost all private insurance, will run into a wall of skepticism from ordinary voters — and not just conservatives who hate expanding the federal government.

Most Americans want better insurance, but they don't want taxes increases to pay for it.

Granted, many Americans agree that the government should guarantee that everyone has adequate health insurance. And, according to Kaiser Family Foundation polls, a growing number support a government-run "single-payer" plan as the way to do that.

But when the details are introduced, public opinion turns contrary. According to the same Kaiser polls, most Americans want better insurance, but they don't want taxes to go up to pay for it. Most also dislike increasing government control over the health care system.

And most people with employer-provided private insurance say they like it — suggesting that they'd hesitate to see it scrapped for a government plan. That's what doomed Bill Clinton's health care bill in 1994; that's why Barack Obama left existing insurance plans pretty much alone. It's not irrational; it's simple aversion to risk.

I haven't even mentioned the most immediate obstacle: A Republican-led Congress isn't going anywhere near Sanders' idea. Instead, Republicans are still trying to repeal President Obama's health care law, which relies on private insurance companies. Their most recent bill, sponsored by GOP Sens. Bill Cassidy of Louisiana and Lindsay Graham of South Carolina, was teetering just short of a majority at the end of the week.

That's why the most important health insurance bill to watch over the next few years may not be Sanders' Big Bang approach, but a less ambitious proposal from Democratic Sen. Chris Murphy of Connecticut. He calls it "Medicare Buy-In."

Murphy's plan wouldn't put everyone into a single government-run health plan. But it would give everyone access to Medicare, the enormously popular government-run plan mainly for those 65 or older. "Everyone" includes users of employer-provided health plans, who could buy into Medicare instead of whatever private plans their companies offered.

What's the hitch? People would have to pay a premium, just as Medicare users do now.

"If I were to design a health care system from scratch, it would be single payer," Murphy told me last week. "The question is how we get there."

"I think even Bernie would admit it's going to be hard to get Congress to pass a bill that outlaws private insurance. Medicare buy-in is an easier lift," he said.

Like Sanders, Murphy hasn't offered detailed cost estimates, but he plans to get that done before he unveils a bill later this year.

"Everything I've seen suggests that a Medicare product will be cheaper than private insurance. The question is how much cheaper," he said.

One more potential benefit: "The price of Medicare will likely go down if the pool gets younger."

Murphy isn't the only Democrat working on an alternative to the Sanders plan. Sen. Brian Schatz of Hawaii has proposed allowing consumers to buy into Medicaid, the insurance program for the poor, which could be less costly but would rely on states to implement. Sen. Debbie Stabenow of Michigan has proposed a more modest bill opening Medicare to anyone 55 or older.

And, in the short run, Republican Lamar Alexander of Tennessee and Democrat Patty Murray of Washington are working on a bipartisan bill to stabilize Obamacare — assuming it isn't repealed first.

Murphy is OK with the competition. "This is a moment when we should hope for a lot of different options," he said.

Sanders should be OK with it, too.

If any of the options for expanding health insurance advance, the Vermont senator will deserve credit for making single payer part of the mainstream debate — and for making ideas that once seemed radical, like simply allowing everyone to buy in to Medicare, look downright conservative.

Doyle McManus is a columnist for the Los Angeles Times. Email: doyle.mcmanus@latimes.com

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