Republican vigilance about keeping illegal voters from voting is democratically equivalent to Democratic vigilance against Republican attempts to suppress the legal vote. Republican vigilance has the semi-intended side-effect of suppressing likely Democratic votes. And huge Democratic registration and GOTV drives have the semi-intended side-effect of canceling out a large number of Republican votes with illegal ballots. I bet I can tell from your party affiliation which you think is worse.
Voter fraud is similar to voter intimidation. That’s the conclusion Will Wilkinson comes to as he looks at legitimacy and integrity in the democratic process.
And Bill Hobbs has an archive of incidents of reported and suspected election fraud.