Two options for Purge 4
1. Senator Charlie was actually evil, had killed her whole family herself in order to get to power. (She will not get ride of the Purge but actually just make it continue). Pretending to be on the "against purge" peoples side, she could both become the president and get ride of the other political candidates etc so she could gain more power herself and take the purge to a whole new level.
(I mean, didn't she seem a bit too good?)
2. The whole world is now having the purge night, so now there's a global purge night.