This is the one I see as most likely. Post an ICE squad outside random polling places in big cities throughout the day (and every day in states with early voting), ostensibly to “ensure vote security” and “make sure illegal immigrants don’t vote like they have before.” Move them around throughout the day so you never know when or where they’ll show up (I don’t think they have the manpower to really sit a squad at every polling place in every big city). That will discourage some non-trivial number of people from showing up to vote for fear of getting murdered or disappeared. Given the margins for everything, that’s probably enough to ensure a landslide win without actually “rigging” anything or cancelling the elections.