The New York Times trolled Trump by headlining
this article noting potential 2020 primary challengers all weekend. Mike Pence managed to stifle laughter while claiming that he would not challenge his boss, but there are still a bunch of juicy possibilities.
The 2016 version of this thread turned out to be the GOAT politics thread and I wanted to get in on the ground floor for 2020.
Some contenders:
Who you got?