I don't think that Trump supports the dissolution of NATO. What he wants is more contribution from the EU nations. US spends close to $600 billion every year on defense purposes, while the military budget of nations such as Germany and England remains as a small percentage if their national GDP. Trump wants the EU nations to contribute in terms of funds, equipment and manpower. And I don't think that there is anything wrong in what he says. Why should the US subsidize the national defense of EU nations? Doesn't make any sense.
There is also a good way of saying "we just won't spend this much on military anymore" and the left would be all behind that, would Trump do that? Or is he just want more for the people who bribed him to be there?
If you spend 800 billion on military and lets say that 100 of that goes to spending on NATO, would you cut it to 700 and not help NATO, or would you keep it at 800 and spend it on Warhawk companies in the USA? That's the real question, if we are talking about a cut, which Trump could have done any time in his 4 year tenure, that would be fine and accepted by everyone, this is why it would be a lot better if we just knew what he would do by his first 4 years, if he didn't then nobody would trust him to do it in another 4 years, could be a big lie.
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.