It is very likely that the Democratic presidential candidate in 2020 will end up campaigning on something he or she calls “Medicare for all.” And no wonder: a recent poll finds that 70 percent of Americans support “Medicare for all.”

Here’s a very brief description of that term from progressive rock star and Democratic Congresswoman-elect Alexandria Ocasio-Cortez:

People don’t want overly complicated choice between pricey, low-quality plans. We want an affordable solution that covers our needs, like the rest of the modern world. Medicare for All:

– Single-payer system

– Covers physical, mental, & dental care

– 0 due *at point of service* — Alexandria Ocasio-Cortez (@AOC) December 2, 2018

Anyone who has any experience with Medicare knows that is not what Medicare is. Traditional Medicare covers relatively little: those who use it aren’t reimbursed for vision and dental services, for example. Also, without purchasing a MediGap supplemental plan, Medicare comes with deductibles and copays. Traditional Medicare is not “free at the point of delivery” and monthly premiums are automatically deducted from recipients’ Social Security checks. Millions of seniors have opted out of traditional Medicare and instead receive Medicare Advantage, which more resembles traditional private health insurance.

Even some progressives acknowledge that “Medicare for all” isn’t what many on the left think it is. “The more you look at it, the more ‘Medicare for all’ is, well, misleading,” New York‘s Ed Kilgore wrote last year. In fact, Kilgore said, Medicare isn’t at all what Democrats actually want, which is single-payer health insurance.

There is a simple reason why Democrats prefer to use the term “Medicare for all” over “single-payer”: it polls better.

But if “Medicare for all” is not the right way to describe a single-payer plan, what is? Would the troubled VA system work as the proper analogy? The answer is no. The VA is more like the UK’s National Health Service, a single provider of health care services paid for by the government. (Though ironically, a recent reform of the VA expanded its reliance on the private sector to deliver health care to vets.)

The proper comparison is to another existing government health care program: Medicaid. Medicaid, which is funded jointly by the federal and state governments, insures millions of low-income patients, children, and the disabled, or an estimated 20 percent of all adults. There are no monthly premiums and no deductibles (though there can be small copays for pharmaceutical drugs).

The Medicaid program is the closest America has to “single-payer,” in that one payer, Medicaid, pays for health care services. But you will not find many single-payer proponents touting the Medicaid system, which was expanded in most states with the passage of the Affordable Care Act. That is because Medicaid has created unsustainable costs for many states and is in need of reform.

My mother is disabled, with congestive heart failure, COPD, and insulin-dependent diabetes, and must take a battery of medications in order to live. She is on Medicaid. I have been helping her navigate her benefits and it’s certainly been an eye-opening experience.

My mother has had problems getting some of her medications filled because Medicaid requires prior authorization for many of them, whereas under private health insurance that wouldn’t be a problem because she would simply call her doctor and make an appointment. Yet on Medicaid she’s had problems even finding a doctor, since most doctors will not take Medicaid. Ultimately, my mother had to pay a substantial sum out of pocket to a doctor that does not take Medicaid just to get refills on her life-saving medicine.

Other problems persisted. My mother had difficulty getting her insulin filled because Medicaid does not cover the type of insulin she uses. She was forced to rely on insulin samples from her doctor, some of which were expired and made her ill, until she was able to get a refill when her Medicare Part D coverage kicked in.

My mom’s terrible experiences with Medicaid are hardly unique. While there isn’t a study that’s tracked doctors’ participation in Medicaid over time, a 2013 survey from the CDC showed that only 68.9 percent of doctors were receiving new Medicaid patients, compared to 84.7 percent of private insurance patients and 83.7 percent of Medicare patients. Another 2013 survey from Oregon showed that outcomes between those on Medicaid and those who were uninsured were not statistically different.

Fiscally, Medicaid is in desperate need of reform. It is a driver of our unsustainable national debt and is wreaking havoc on state budgets. Expanded Medicaid spending is forcing state governments to choose between raising taxes and cutting other services.

We already know the future if single-payer health care is implemented in the United States: worse quality of care, decisions made by unaccountable bureaucrats instead of doctors, and unsustainable spending and debt.

Yet opposing that future doesn’t mean conservatives can just say no. The problem of affordable health care is a serious one. For example, in 2019, my health insurance premiums will be $40 more than my car note.

Conservatives need to promote alternatives such as direct primary care where patients pay monthly fees to their family doctors in exchange for service. Health insurance should be reserved for truly emergency and catastrophic cases.

As long as conservatives continue to defend the status quo—or the pre-Obamacare era—single payer is all but inevitable. And judging from America’s ongoing experiment with Medicaid, that would be a disaster for both the nation’s finances and wellbeing.