A recent NBC/WSJ poll shows just 4 percent of Americans believe Obamacare is working well the way it is. As evident in the 2016 presidential election, there are few politicians left in this camp: President Trump and Republicans want the law repealed. Sen. Bernie Sanders supports single-payer healthcare. Even Hillary Clinton believed the law needed to be changed significantly.

American voters chose wisely, overwhelmingly electing proponents of repeal. Today, Republicans have control of both houses of Congress and the White House. They've never had a better opportunity to repeal Obamacare, which is what many Americans want them to do.

But it's important that lawmakers understand the stakes: if they fail to repeal Obamacare now, the law's continued "death spiral" (to use the words of Aetna's CEO) and the public's dissatisfaction with the law will keep us on a path toward a single-payer system that would offer all Americans only one form of insurance, one completely controlled and financed by the government.

Obamacare was a big step, but not the first one, toward government-run healthcare. "The Great Society" was the camel's nose under the tent. These programs were introduced as safety-net programs, but once the federal government began providing health insurance for all senior citizens (Medicare) and low-income people (Medicaid), it became much easier for big-government supporters to expand the eligibility and benefits provided. While expanding benefits to the public may sound like a good thing, there are costs, in terms of taxpayer dollars, public debt, and perhaps most importantly, reduced options for patients.

Today, 55.3 million seniors are on Medicare, and 74.4 million people are on Medicaid. There are some dual-eligible people (nearly 10 million), but when you include Tricare enrollment and other veteran's health programs, today about 40 percent of all Americans have a government health insurance plan.

Supporters of single-payer use the expression "Medicare for all" to advocate for single-payer, and more tepid Democrats might support "Medicare for more" or lowering the eligibility age as another step in expanding government-provided health care. The messaging focuses on Medicare, not Medicaid, because most Medicare beneficiaries are happywith their coverage and access to care, while sadly Medicaid falls shorton reimbursement, access, and outcomes.

But the reality is that single-payer in the United States is more likely to be "Medicaid for all," than Medicare for all. Consider that, even before Obamacare, Medicaid covered nearly half of U.S. births. Obamacare's Medicaid expansion was a giant leap forward for those who favor "universal coverage." The latest figures show 11.7 million more have enrolled in Medicaid since Obamacare took effect.

Importantly, many (half, according to an estimate from the Foundation for Government Accountability) of those who have recently enrolled in the Medicaid expansion were previously insured in a private health plan, on their own or through an employer.

This "crowd-out" effect is an excellent political strategy for single-payer advocates: Once the benefits are extended, it's much harder for the government to rein them in (but taxpayers should wonder about the why their money is going to move people from private plans to Medicaid, where health access and outcomes are worse).

While Obamacare's original intent was for all 50 states to expand Medicaid, 19 have refused. But this means 31 states, and the District of Columbia, have taken the bait. Generous federal money proved too much for even some Republican governors to resist. This is now causing trouble for Republican senators, who would like to repeal Obamacare (and perhaps replace it) but are concerned about how states will fair if the Medicaid expansion is repealed.

But mark my words: if Republicans don't undo Obamacare now, we will remain on a path to single-payer. Future Democratic governments (or perhaps big-government Republicans) will take the easy, popular (but misguided) road to expanding Medicaid eligibility even more. Today the threshold is 138 percent of the federal poverty line. If Obamacare stays on the books, what will it be 10 years from now? How many millions more will be added?

Democrats, like candidate Clinton, are transparent about the next major change they want: a "public option." They'd add this option now, as private options have been dwindling. Disguised as a government plan that would simply "create greater insurance competition" for private plans, a public option would surely push out the few (in many places, the only) insurance companies left. Government competition isn't fair; it'd be like referees playing against the team. The result would be only one option: ultimately, single-payer.

Philip Klein, managing editor of the Washington Examiner, called one Republican replacement plan (Cassidy/Collins) the "Obamacare Forever" plan, because it let some states keep Obamacare as is. But the reality is that Obamacare cannot last forever. If Republicans leave Obamacare as it is, we can be sure that Democrats ultimately will not. Either it will be repealed or it will stay in place and only become a vehicle for the Left to continue their march toward single-payer. We must repeal it now, or brace for the consequence.

Hadley Heath Manning (@HadleyHeath) is a contributor to the Washington Examiner's Beltway Confidential blog. She is a senior policy analyst and director of health policy at the Independent Women's Forum, and a Tony Blankley Fellow at the Steamboat Institute.