In order to get single-payer, you must overcome the American Medical Association, Big Pharma, the Health Insurance Industry and all of the Democratic and Republican members of Congress and the Senate who receive their support to get re-elected.

And you have to also overcome Hillary Clinton's ties to all of the above if she is elected President. 

CNN Feb 11, 2016

"Their biggest recipient? Clinton. She collected $336,416 in donations, over a third of the total contributions during the 2016 presidential campaign. The next biggest recipient was Republican candidate Jeb Bush, who collected less than half the amount of Clinton. Trump received the least in donations: $1,010, enough to buy one Daraprim pill. 

The Health Insurance industries deal with Obama to keep from fighting Obamacare was mandatory health insurance for healthy people enforced by the IRS.  That isn't working so the health insurance industry is refusing to participate.  They can't be forced to participate.