Step 1: Refuse to confirm a SCOTUS judge for a year.
Step 2: Install a judge you prefer.
Step 3: Get a SCOTUS ruling upholding a voter purge law that disproportionately impacts people who are more likely to vote for your opponents.

Voter purges aren’t about getting rid of invalid registrations. They’re about suppressing votes. The US, unfortunately, has a long history of finding ways to disenfranchise a group without explicitly identifying them. Look up where “grandfather clause” came from.

The modern version is subtler, but it works like this:

You want more people from group A to be able to vote than group B. Find some classification that applies to more members of group B than group A. Target that classification, and you change the balance of the electorate.

What Ohio did was notice that members of one major party tend to vote in every election, while members of the other tend to skip elections where they don’t feel they have a good choice.

Technically they targeted occasional voters.
Effectively they targeted a political party.