Democratic Primaries

He would come out and say states need to postpone elections because it's not safe for voters in major US cities to cast their ballot. Of course, he doesn't have authority to get that done - but he can put pressure on states.

1) Ask each state to postpone their elections.
2) IF the state refuses to, he will up the National Guard to every polling station in America's cities (under the idea they're the hardest hit) to protect order and make sure voting is done 'efficiently and within specific guidelines).
3) Maybe some states with Republicans governors and legislatures, like, say Ohio or Florida, give in and postpone. How can you have a legitimate election at that point if some states vote and others don't?

And if anyone pushes back, Trump could just claim he's following the lead of what the Democratic Party did earlier in the year.