From the Powerlineblog.com site. 

Walter Cronkite to Larry King:

The only thing that could damage the turnout would be the threats that might be implied, as many of the new registrees are challenged as to their various things. Their spelling of their name and the state where they really come from, whether they're immigrants or not, do they have passports, all that kind of thing. If they are challenged at the polls, as they line up to go into the polls, they may fear having to answer all those questions. Particularly if they do have anything wrong about them and shouldn't vote.

Via Tom von Gremp