The biggest challenge to this sort of thing is that it has had disastrous results in every state where it was adopted in some form or another -- including Bernie Sanders' home state of Vermont, which dropped their "Green Mountain Care" in 2014 after only three years.
Sending Bernie Sanders out to promote single-payer health care is like sending Mitt Romney out to overturn Obamacare.
Vermont abandoned single-payer health care because they finally figured out that their state budget is something like $4.9 billion per year and single payer would cost $4.6 billion....nearly double the state budget.
Taxes would have had to sky rocket to pay for this nightmare.