WASHINGTON — Democrats set to take the debate stage in Houston have spent hours tussling on TV over decriminalizing border crossings, forgiving billions in student debt and how best to tackle climate change.

But one issue has dominated the discussions so far: “Medicare for All,” a radical approach to universal health care championed by Sens. Bernie Sanders, Elizabeth Warren and other left-leaning presidential hopefuls that has repeatedly derailed the debates into tit-for-tat bickering over wonky health care specifics.

There’s reason it’s been such a big part of the discussion: As extreme as some would brand the proposal to get rid of private health insurance and establish a universal government system, it has caught fire with more than just progressives. Several polls indicate it has the support of most voters — even in Texas, where some 55 percent of people are in favor, according to at least one poll by the Texas Medical Center.

Other polls show the switch to a government health care system has at least the same level of support from Texans as keeping the current system, with its highest-in-the-world prescription drug costs and its failure to help millions of Americans diagnosed with medical conditions that push the cost of private insurance out of reach for them.

Texas, which leads the nation in residents without health insurance, is clearly ready to consider the pros and cons. Health care analysts, however, have been struggling to do just that, saying the proposals pitched by Democrats so far are too vague for any real study of how it would work. They’ve been scratching their heads for months and waiting for details to emerge that would help them gauge the potential impact on American taxpayers and the economy.

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“If we start out from a very high plain and just say, ‘That means everybody is covered’ … that’s good for Texans, and that’s good for Texas,” said Arthur “Tim” Garson, director of the Health Policy Institute of the Texas Medical Center. “The real question for all the candidates is, ‘OK how are you going to get there?’ — and I’ve not heard that yet.”

Republicans, meanwhile, are starting to take more seriously what they were once able to dismiss as an extreme socialist idea.

“It’s very real,” said Rep. Kevin Brady, R-The Woodlands, the top Republican on the powerful House Ways and Means Committee. “I’ve never seen a health care idea gain so much momentum so quickly.”

Brady, who spent much of Congress’ August recess visiting hospitals and holding town halls in the Houston area, said Texans have been “stunned” by his warnings of what he believes to be the dangers of the proposal: Massive tax increases, millions uprooted from their current insurance plans and hospitals taking massive financial hits.

“People are very, very worried,” Brady said. “I think the most common phrase, feedback I get is ‘disastrous.’”

Lingering questions

Democrats in Congress have proposed legislation that would create a two-year transition from the current system to a government system. During that time, people could buy into the Medicare program early. It would allow the sale of health insurance coverage beyond what Medicare-for-all offers, including additional benefits that an employer may provide to employees or their dependents.

The legislation would create a Medicare for All trust fund in the Treasury to pay for the program.

But among the biggest questions is how to cover the cost of the program, which is estimated to be at least $30 trillion. The candidates have acknowledged they’d raise taxes, though the size of the tax increase remains unclear. Also yet-to-be-determined is what the net difference would be when people no longer pay toward their private insurance.

Another major question is what role — if any — private insurers would play. While most other countries in the world have some sort of universal health care program, they also have some role for private companies, whether that’s paying for prescription medication or an optional add-on to the government plan, Garson said.

“There is not a system I’m aware of in the world that the government pays for absolutely everything for absolutely everybody — and that’s what Bernie Sanders is talking about,” he said.

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Vivian Ho, director of the Center for Health and Biosciences at Rice University’s Baker Institute for Public Policy, is even more skeptical.

Ho said that health care providers stand to take a massive financial hit — as much as a 22-percent gap between costs and the money they’d be reimbursed from Medicare. And she so far hasn’t seen any convincing explanation for how that gap would be closed, though proponents of the plan say clinics would benefit from major administrative savings because they’d no longer have to deal with insurance companies.

“There’s not enough detail,” Ho said about the existing proposals. “It really bugs me because … anybody who’s proposing Medicare-for-all hasn’t sat down and learned enough about the health care system to realize what you need to do to get things to work.”

Sanders, who has made the issue central to his campaign, has pitched it from the debate stage as a much-needed overhaul for a broken system.

“Right now we have a dysfunctional health care system: 87 million uninsured or underinsured, 500,000 Americans every year going bankrupt because of medical bills … while the health care industry makes tens of billions of dollars in profit,” he said in July. “Health care is a human right, not a privilege. I believe that. I will fight for that.”

Medicare for All, Sanders argues, is comprehensive — it would cover any and all health care needs, “it will finally include dental care, hearing aids and eyeglasses.”

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Sanders would pay for it by charging employers and with new taxes — especially on the wealthy — though he claims that under his plan, the average middle class family would pay $4,400 less than they’re spending now on private health insurance.

As Warren put it at the last debate: “Costs will go up for billionaires and go up for corporations. For middle-class families, costs — total costs — will go down.”

The pitch seems to be playing well in Texas.

Lone Star support

The most recent Texas Medical Center consumer health survey, published in November, found 55 percent of Texans supported expanding Medicare to all U.S. adults. Nearly two thirds said it’s important or very important that a candidate also support it to earn their vote. A University of Texas-Tyler poll in July found 54 percent in favor. A March University of Texas/Texas Tribune poll found slightly less support — just 44 percent — though nearly as many were in favor of a universal system as the 45 percent who said they prefer the current system.

Six Texas Democrats — U.S. Reps. Al Green, Sheila Jackson Lee, Veronica Escobar, Vicente Gonzalez, Marc Veasey and Lloyd Doggett — have signed onto the House version of Sanders’ Medicare for All pitch, which has drawn the backing of at least 117 Democrats.

Doggett, an Austin Democrat who serves on committees with jurisdiction over Medicare and health care, said he supports any proposal that would expand Medicare and extend it to more Americans, though he said he’s not totally sold on Medicare for All as the right approach. He said Medicare for All is “a good aspiration and sets the standard we’d like: To extend universal coverage, and do it promptly.”

Doggett has also signed onto proposals such as Medicare for America, which would extend the government program as an option to all Americans, though they could choose to keep their employer-provider health plan instead.

Texas, especially, has much to gain as it has the highest uninsured rate in the nation, in part because state leaders have rejected Medicaid expansions under the Affordable Care Act, he noted.

“One of the things we’ve got to do, recognizing political realities here in Texas — they’re Medicaid deniers, much the way they’re climate change deniers — is to find ways to cover poor people in Texas,” he said. “That’s one of the areas Medicare for All and Medicare for America have appeal.”

ben.wermund@chron.com