I would guess that the whole nation would be cheering for that, imagine a situation where the government becomes an insurance company, they are failing to even do that, any candidate that explain this clearly would make a big profit.
First of all, you could cap the income of medicine and hospital companies, if you end up with 4-5 trillion a year spent on healthcare when the same amount of sickness causes it to be 500-600 billion just across the border, that's a problem, and you could do free healthcare for 800 billion that they are spending right now.
Imagine a USA that has very low amount of military power, lets say 100 billion a year, and instead the rest of the money goes to free healthcare for everyone? That candidate would win with 100+ million votes.
No one will do that, not even the Libertarian Party or the Green Party. The retarded medical care system in the United States will stay for ever. Even OTC drugs cost 10x or 20x of the prices in Canada or Mexico. Medical procedures are insanely expensive. The co-pay amount itself is more than what Canadians pay for their complete treatment. But the tragedy is that no one want to change any of that. And then there is this prescription drug (opioid) epidemic which is killing more than 100,000 Americans every year. No one really care. Ask any white collar American and they will tell you that these people are all junkies and they deserve to die.