There is a pretty long history of voting machines being vulnerable to hacking. The AVS WinVote was determined to be fairly vulnerable to attack. Could AI help here? Well, maybe. A number of the attacks were physical in nature. So, while AI might make the compromise easier, it relies on a human getting access. There were also remote attacks which could be launched over WiFi, if that was enabled. Though since you would need to be in somewhat close proximity to the device, it again needs someone to get AI in close proximity.

And this is where the fears around hacked elections tend to be a bit overblown. It's very likely that the voting machines have unknown vulnerabilities. And AI may be useful in finding and possibly exploiting those. But, voting in the US is a very dispersed affair, with much of the infrastructure for it not attached to the internet. Hacking any meaningful number of machines and altering any meaningful number of votes is going to require a lot of people coordinating. This isn't impossible, but it increased the chance of detection.

And then there is the issue of the paper trail. While not every State and precinct uses voting machines with a human verifiable paper trail, a lot do. And the fears over hacking helped push that forward. Just using my own precinct as an example, I vote by filling in boxes on a physical piece of paper. That then gets fed into a machine for counting and dropped into a secure lock box. In the event the machine fails or there are questions around the votes recorded by the machine, the paper ballots can be pulled out and verified against the machine count. Maybe someday AI will be able to retroactively alter those paper ballots, but that's a long way off. It's also why the Trump Administration has talked about seizing ballots. By breaking the chain of custody, they can bring into question election results they don't like, assuming they don't try to alter the seized ballot counts outright.

The short answer is, AI isn't really a threat to elections in the US at the moment. The real threat is the corruption in the current administration and their blatant attempts to undermine democracy.