General Discussion

If a passport is part of the requirement, then poor, rural American citizens may be intentionally discriminated against. Farmers in particular may never have traveled outside the country, so they never saw a need for one.
Also the elderly who may have had a passport at one time, but no longer travel and have let it lapse. My wife and I are in that group, and I've just got my documents for passport renewal together. We'll be starting the process soon.

I haven't gotten any in-depth determination as to which party will lose the most votes, but that may not be the point of it. Perhaps it's the start of a long term restructuring of the voting process that will eventually trim the roles down to a much smaller percentage of citizens being allowed to vote. The smaller the number, the easier it is to control the outcome.