We won’t rehearse the familiar points about Medicare for All: it’s good, it’s needed, it’s what the people want — as Fox News recently found out the hard way.

But Medicare for All is more than just a matter of fixing our broken health-care system. And it’s more than just a good policy. It’s the perfect fight to pick with our ruling class — one that can unlock the power of a mass, working-class movement in the United States.

We don’t believe this because we think health care is somehow naturally more important than other issues. On moral grounds, it’s hard to find an injustice more tragic than migrant detention camps, and we could be convinced that any number of causes are more morally urgent than Medicare for All. On scientific grounds, the imminent threat of climate disaster is surely the most pressing issue, not just for the Left but for humanity as a whole. But on political grounds, if we want to take the nascent left renaissance in America and turn it into a durable, working-class movement in the 2020s — a precondition for addressing more morally and more scientifically urgent issues of the day — the fight for Medicare for All must be at the very top of the Left’s priorities.

Despite modest growth in the wake of Bernie Sanders’s 2016 primary run, the American left is still near a historical nadir in terms of its political power and, not uncoincidentally, in relative isolation from the working-class people, institutions, and culture it would need to win real power and influence on the national political stage. Forget our ambivalence about class centrality: what really matters right now is our lack of class rootedness.

The central question at present must be: How do we anchor our politics in the lives of working people and institutions? The unmoored left does not get to decide what issues should be prioritized based on its own determination of moral or objective exigency. Rather, we must construct our strategy on the basis of a political analysis of the contemporary situation, considering first and foremost what will attract millions of people to the American left in a concrete and material way. And for that, we believe that there is no better fight than the one for Medicare for All.

It’s easy to lose sight of this simple fact when embroiled in the myriad and complicated debates that exist on the Left, but most people won’t be attracted to left politics just because we have the correct political positions or out of an abstract commitment to justice. The best means of expanding our ranks from the thousands to the millions is by demonstrating that not only does socialist policy work, but that it very rapidly makes a lot of people’s lives noticeably better.