In my state, as a first time voter registrant, you have to list your social security number or drivers licence number on your application. If you're in the field registering at a drive and don't want to list that info on your application or don't have that info on hand, then you still get registered but are flagged at your polling place, to show either one of those IDs at the voting place, and your vote is on a provisional ballot. The next time you vote, you don't need to show ID.
My state made everyone show proof of citizenship, for their driver's licenses.... I had to go back in, when renewing mine, and show my birth certificate or maybe I used my passport, as proof of citizenship.... this was several years ago....had something to do with a new Federal Law, imposed on all the States.
And SS numbers are only for citizens, non citizens get TIN numbers not SS #s
When you require that proof of citizenship, in the field....like at a school registration drive made up of volunteers, students may not want to put their state driver's licence number or SS number on the form, and prefer going in to a registrar office to submit it, or show ID when voting for the first time, at the polling place, or you may just not have that info on you at the registration drive.
Your republican side, is simply trying to keep many students, Nationwide, from registering at a registration drive at their schools. That is the Republican Congress critter GOAL!
When States have measures in place that already prove registrant citizenship, like mine....before they vote for the first time.