There would be fierce conservative resistance to the plan.

Jonathan—professor and chair of Social Medicine and professor of Health Policy & Management at the University of North Carolina-Chapel Hill, "The Virtues and Vices of Single-Payer Health Care," The New England Journal of Medicine, Vol. 374, p. 1401-1403

The substantive virtues of single-payer programs are compelling. But so are their political liabilities. Medicare for All, which aims to constrain health care spending, faces intense opposition from insurers, the medical care industry, and much of organized medicine. It would trigger fierce resistance from conservatives and the business community and anxiety in many insured Americans fearful about changing coverage and the specter of rationing. The ACA's comparatively conservative reform approach inspired false charges of "socialized medicine," "pulling the plug on grandma," and "death panels." It takes only a little imagination -- or a look back at the history books -- to predict the reactions that an actual single-payer plan would evoke.

Single payer would also require the adoption of large-scale tax increases. Although Americans would save money by not paying premiums to private insurers, the politics of moving immense levels of health care spending visibly into the federal budget are daunting, given the prevailing antitax sentiment. Furthermore, converting our long-established patchwork of payers into a single program would require a substantial overhaul of the status quo, including the ACA.4 Then there are the familiar institutional barriers to major reform within U.S. government, including the necessity of securing a supermajority of 60 votes in the Senate to overcome a filibuster.

In short, single payer has no realistic path to enactment in the foreseeable future. It remains an aspiration more than a viable reform program. Single-payer supporters have not articulated a convincing strategy for overcoming the formidable obstacles that stand in its way. Nor have they, despite substantial public support for single payer, succeeded in mobilizing a social movement that could potentially break down those barriers. The pressing question is not about whether Medicare for All can be enacted during the next presidential administration -- it can't -- but where health care reform goes from here.