So many, mostly republicans are pushing for voter ID. There is no rule in this country to have a picture ID, but every citizen does have the right to vote. I would consider it a fundamental conservative belief that we should try to limit rule/regs if not necessary and If you are going to require something like this I would think there should be good reason. However there doesn't seem to be any.
I can see no other real reason to push this except to deter some voters, mainly minority/lower income/urban voters all who tend to be more liberal. If nothing else this is a bad PR move on the part of conservatives.