A national ID is a terrible and horrible, no good idea. The next President could be like Obama, he'd give those ID to anyone crossing the border. We already have states giving ID's and drivers licenses to illegals and the federal government gives them SS numbers and such. Another ID will offer no more protection against vote fraud than the ID's from the states.
I don't have the same take on that, but I do think it's a horrific idea.
For by requiring ID to vote, you allow the state to tie your vote back to you. IE: the voter center volunteer notes your ID and issues you *YOUR* ballot)
Which means a vindictive politician would then be able to compile a list of those that didn't vote for him.