Pollster Mark Blumenthal analyzes RFK's claims about exit polling, beginning here:
http://www.mysterypollster.com/main/2006/06/is_rfk_jr_right.html
The Volokh Conspiracy (which is a blog of mostly conservative and/or libertarian lawyers and law professors) has some posts with links to various election law experts and other sources, starting here:
http://volokh.com/archives/archive_2006_06_04-2006_06_10.shtml#1149520989
As to the general topic of election irregularities, the basic problem is that there are two kinds of vote fraud that happen to some degree:
1. People being allowed to vote who shouldn't, either because they already voted, aren't citizens, don't reside in the district in which they're trying to vote, or are otherwise ineligible by law (e.g. convicted felons).
2. People who are entitled to vote being turned away by election officials, because they supposedly haven't provided sufficient proof that they aren't actually in category 1, or who simply don't bother to show up at the polls because they think this will happen.
They're both legitimate problems that a good electoral system should try to address. What causes all the fighting is:
(a) to some degree there's a trade-off between the two: you can reduce category 1 by toughening up the proof voters must produce to demonstrate their identity and eligibility, but that's going to increase category 2, and vice versa,
and
(b) Republicans believe that they're hurt mostly by category 1, and Democrats believe that they're hurt mostly by category 2.
So both parties want to crack down on electoral irregularities, but they each want to focus on the one that hurts them.
