The Constitution lets the electoral college choose the winner
 

Conventional wisdom tells us that the electoral college requires that the person who lost the popular vote this year must nonetheless become our president. That view is an insult to our framers. It is compelled by nothing in our Constitution. It should be rejected by anyone with any understanding of our democratic traditions  - most important, the electors themselves. The framers believed, as Alexander Hamilton put it, that "the sense of the people should operate in the choice of the [president]." But no nation had ever tried that idea before. So the framers created a safety valve on the people's choice. Like a judge reviewing a jury verdict, where the people voted, the electoral college was ...

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There is a rule book to this. Most states bind electors to their parties' winner.

It's not like a trial jury nullification of guilt by circumstances.

The Constitution also forbids the president from being indebted to any foreign nation or persons.

"Article 1, Section 9 of the Constitution, which bars office holders from accepting “any present, emolument, office, or title, of any kind whatever, from any king, prince, or foreign state.”

This possibly bars Trump from being elected by the EC, unless he gets rid of his corporate assets, prior to entering office.