“It’s an unbelievably complex subject,” President Trump said in February, discussing the Republican plan to repeal the Affordable Care Act. “Nobody knew health care could be so complicated.” It was a typically absurd proclamation for the president, who more recently bragged about how quickly he mastered “everything there was to know about health care.”

As complicated as health care is, the case against Trump’s health-care bill is simple. Trump promised to provide “insurance for everybody”; the American Health Care Act passed by the House last month would cause 23 million Americans to lose their coverage. Trump promised not to cut Medicaid; the AHCA would slash more than $800 billion from the program. Trump promised to protect people with preexisting conditions; the AHCA would allow discrimination against such patients. As National Nurses United Executive Director RoseAnn DeMoro put it, Republicans are essentially proposing “a 21st Century version of ‘Lord of the Flies.’ ”

For Democrats, opposing Trump’s plan, which a measly 8 percent of Americans support in its current form, is a no-brainer. But with health care emerging as the American people’s top concern , according to recent polls, Democrats would be wise to seize the moment, go on the offensive and rally around a bold alternative to the Republican Party’s backward vision. It’s time for progressives and Democrats to unite behind Medicare for all.

Under a Medicare-for-all, single-payer system, the United States would join virtually every other Western country in recognizing health care as a fundamental right and providing insurance for every citizen. It would reduce the burden on employers, which bear the brunt of the cost of insurance today, and it would bring down overall health-care costs because Medicare is more efficient than for-profit private insurance. It would be paid for with tax hikes on the wealthiest Americans, including a financial transactions tax that would curb risky high-frequency trading.

Contrary to how it is often portrayed, this is not some left-wing fantasy but an idea with widespread across-the-aisle support. An April survey from the Economist/YouGov showed that 60 percent of Americans support “expanding Medicare to provide health insurance to every American,” including a majority of independents and nearly half of self-identified Republicans. Likewise, a Gallup poll conducted last month found that a majority of Americans would like to see a single-payer system implemented. (Given how deeply Medicare is woven into the fabric of our society, I prefer the term “Medicare for all” over the wonky “single-payer.”)

This is not to say that Democrats should stop defending the Affordable Care Act, which is more popular now that it is being threatened than ever before. The law was clearly a major step forward, as evidenced by the 20 million Americans who gained coverage because of it. But the most compelling argument for the Affordable Care Act was always that it was just that: not the final destination but a step in the right direction. “For me, this legislation represents progress toward universal health care for all Americans,” Rep. Keith Ellison (D-Minn.), a longtime supporter of Medicare for all, said when it passed in 2010 . “It is a beginning — and an important one.”

Today, with Republicans fighting to put universal coverage further out of reach, more progressives and Democrats are recognizing that now is the moment to push Medicare for all. A bill introduced by Rep. John Conyers Jr. (D-Mich.) in the House has 112 co-sponsors, representing a solid majority of the Democratic caucus, up from just over 60 in the last Congress. Sen. Bernie Sanders (I-Vt.), who made Medicare for all a central plank of his presidential campaign platform, is preparing to introduce a bill in the Senate. And last week, supporters of Medicare for all scored a big victory when the California Senate advanced a state-level single-payer bill that DeMoro hailed as a “moral model” for the country.

Looking ahead to 2018, strong progressive candidates are already making universal coverage part of their pitch to voters. In Iowa, nurse and union leader Cathy Glasson has launched a gubernatorial bid with a promise to provide “universal healthcare to cover every Iowan.” And in Maryland, former NAACP president Ben Jealous, who endorsed Sanders in 2016, is running for governor, pledging to “ensure that every citizen” in the state is covered.

It will take smart organizing and tireless work to make it a reality, but Medicare for all is an idea whose time has come. With organizations such as Our Revolution, National Nurses United and the Working Families Party leading the fight, though, the movement for Medicare for all is gaining momentum every day.

During the floor debate over the Affordable Care Act, Sanders declared, “The day will come, although I recognize it is not today, when the Congress . . . will finally proclaim that health care is a right of all people and not just a privilege.” He was right then, and he’s right now. But it won’t happen until progressives drive the debate to the point that Medicare for all is seen not as impossible, but inevitable.