This is a predictable play. This had a highish likelihood of happening the moment they announced the massive, rapid funding and personnel expansion. Now that "abolish ICE" (ICE being their critically-important newly-empowered end-run around Posse Comitatus) is trending, they basically
have to play every card they've got, or risk seeing their project set back by at least a few years, just as it's gaining steam. It'll take longer to capture enough of the courts and military that they don't need ICE and its bullshit "but immigration enforcement must have special otherwise-unconstitutional powers" smoke-screen of a justification any more.
I also expect:
1) Lawsuits, subpoenas, and indictments against and of elections offices and key officials in Democratic areas of vulnerable Republican districts, timed to mess with their ability to even function. If it suppresses the vote that's a "nice to have" but mostly this is to sow uncertainty about the elections both by generating ginned-up headlines (it doesn't matter if the investigations actually find anything or go anywhere) and by delaying vote counting and causing chaos (e.g. very long lines) on Election Day, which opens up greater space for the GOP to act after the elections.
2) Challenges of the outcomes by the administration and their proxies, and outright calls for Republicans to pull certification tricks akin to the fake-elector crime they attempted in '20. This would be supported by #1, and by ICE-created chaos and vote suppression.
Incidentally, the ICE intervention can take many forms, the most extreme of which (and most effective to the admin) is triggering violence (a lot of people are going to react poorly to being asked "papers, please" by a small squad of armed & armored federal thugs on the way to vote) that actually shuts down polling places in key locations. This both heavily suppresses the vote in areas they've targeted, and serves their "chaos! Democrats are trying to cheat by letting illegals vote! See how much they freak out when we don't let them?" narrative. The lighter version is some cautious shows-of-force and unrealized threats ahead of time, aimed at gentler levels of vote suppression (if you're a citizen but have an accent and aren't white, you might think twice about your odds of getting to the polls without getting locked up for a day or two and losing perhaps five figures you may not have attaining your release, and just stay home, even if ICE ends up not showing or just doing some show-of-force drive-bys that end up all over social media)
I'd love to know what, if anything, state governments are planning to prevent any of this. I've personally not been able to think of a single effective thing they can do about it as far as actually keeping it from happening or recovering quickly from the material harm it does (winning much later in the court of public opinion, for whatever that's worth, is another matter, as is eventually winning in court) but maybe there's something.
(I rate all the above fairly likely, in some form; my outside-but-not-impossible-odds guess is they'll seize some ballot drop boxes or enroute mail-in ballots with nebulous claims of wrongdoing that don't go anywhere but do fuck up specific districts' voting processes, with, as usual, no relief from the courts because by the time anything can be done about it it's a fait accompli and nobody's gonna trust those ballots after the feds have had them, anyway)