It's going to be difficult with our current policies because we've erred on the side of making it as easy as possible for everyone to vote. We don't have a complete whitelist of citizens, it's against the law to require proof of citizenship to register to vote (unless that changed recently) and address verification in most jurisdictions isn't done more than the first time unless it's challenged.

To be clear, though, I don't think non-citizens are voting en-masse. My concern is that if you aren't even verifying they're citizens, you probably aren't really verifying that they are a real and unique person that isn't already registered.

Honestly I think if we actually wanted secure elections, we'd start with the red teaming and go from there. The signal to noise ratio of fraud is too meaningless to resolve without tightening up rules, which the results of the red teaming would give you the political capital to do.