If you think it’s only American media that’s been turned upside down by a tweet like this, I’m already doing interviews on the subject with German and Spanish television, and have turned down requests from still other countries.
I’m saying the same thing about this that everyone else who knows the law is saying. Some legal questions are complex, this one is not: the President has no power to change the date of the election unilaterally. The current date is fixed by statute. For Congress to change it, a bill would have to pass the House and survive a filibuster in the Senate.
On top of that, the Constitution, via the 20th Amendment, terminates the terms of current Senators and Representatives on Jan. 3rd and those of the President and Vice President on Jan. 20th.