The issue of health care should not be a liability for the Democrats. Yet for years after its passage, ObamaCare's popularity sagged. The health-care reform law was byzantine and underfunded, making it difficult for voters to draw a straight line between the law's accomplishments and their own circumstances. Democrats avoided talking about it, leaving Republicans free to demagogue ObamaCare as runaway socialism.

During Tuesday's midterms, however, Democrats finally got their health-care revenge. The issue, more than any other, powered their majority win in the House of Representatives.

Exit polls show that 41 percent of voters named health care as being the most important issue to them in these midterms. Immigration and the economy more or less tied for a distant second, at 23 percent and 21 percent, respectively. Another poll had much smaller margins, but still put health care in the lead at 23 percent, versus 21 percent for immigration and 19 percent for the economy. The focus on health care in 2018 suggests that, at long last, health care broadly — and ObamaCare specifically — has the opportunity to become a winning political issue for Democrats.

Since the 2016 election, ObamaCare's approval has actually flipped: Where before, approval for the health-care package was down by 10 percentage points, now voters favor it by 10 percentage points. In 2016, the law was featured in just 10 percent of political ads supporting Democrats. In 2018, it appeared in more than half. It seems the GOP's repeated efforts to kill ObamaCare in 2017 backfired, pulling voters' attention away from the reform's flaws, and illuminating its accomplishments instead.

In particular, ObamaCare finally put in place regulatory protections for people with pre-existing conditions, forcing insurers to cover them. These rules are overwhelmingly popular. Yet all those aforementioned GOP repeal efforts would've scuttled those protections. Currently, a number of Republican-led states and the Trump administration are pressing a court case claiming that ObamaCare's rules protecting people with pre-existing conditions are unconstitutional. Meanwhile, the White House has also been using its executive leeway in regulatory matters to blow as many holes as possible in ObamaCare's infrastructure.

With their health care at stake, voters have a renewed sense of urgency in preserving and extending the security given to them through ObamaCare. Republicans dealt with this problem in the 2018 campaign by straight up lying, and claiming to support protections for pre-existing conditions. This was brazen. It was also a tacit admission of how politically untenable the GOP's position on health care really is.

Meanwhile, the Trump administration's disruptions, plus the death of ObamaCare's individual mandate thanks to the GOP's tax cuts, both conspired to drive premiums ever higher. This served to keep American voters' attention focused squarely on the issue.

Republicans' ObamaCare repeal efforts would have also gutted Medicaid, the single-payer program that provides health coverage for low-income Americans. Through ObamaCare, Democrats expanded Medicaid. It isn't a perfect program, but it has been able to provide people with reliable and useful coverage, with a minimum number of complications. Plenty of red states initially refused to participate in the expansion, but they've been slowly giving in. Protecting and expanding the program proved to be a winning issue for Democrats in ostensible Trump-friendly states. Democrat Laura Kelly took the governorship of Kansas on Tuesday with a campaign that included support for adopting the Medicaid expansion. Democrat Kendra Horn won a congressional district in deep-red Oklahoma while running on Medicaid expansion. Meanwhile, state referendums to join in the Medicaid expansion were successful in Idaho, Nebraska, and Utah.

But ObamaCare alone is not nearly enough. Premiums are still incredibly high, cost-sharing still results in expensive doctor visits, and around 30 million Americans still lack health coverage. That's where the question of Medicare-for-all comes in. Moving the country to a full blown single-payer system would provide every last American with health insurance via the government. This idea has gained steam, even as the GOP tries its best to tar it as communism run amok: One recent poll found just over half of Republicans actually support the idea.

No fewer than half of all Democrats running in contested House races explicitly endorsed the idea. Plenty more suggested runner-up solutions, like a public option on ObamaCare's exchanges, or the option for younger Americans to begin buying into Medicare over time. The appeal of both ideas is that they could serve as a ratchet, expanding coverage via the government over time to eventually arrive at single-payer by default.

The American public is concerned about rising health-care burdens. In turn, health care proved the great sleeper issue of 2018. True, the headlines have been dominated by President Trump's personality, his bluster, his racism, and his generally loathsome character. Running against Trump as an avatar of American values, and to frame the 2018 as "a battle for America's soul," would seem only natural. That is, after all, what Democrats attempted in 2016. Yet they lost.

This time, Democrats took a more practical approach. They spoke to Americans' urgent need for affordable and humane health care for themselves and their families. And the voters rewarded them for it.