Update: I’ve somewhat changed my view about whether the challenge proceeds county-by-county. Sort of yes, sort of no, but I think the remedy is a statewide redo.
Brian Martin points out one in comments: Election contests proceed county-by-county. You go to court in one county, make your proof in hopes to get one of two remedies (a redo or a change of result, depending on what you prove). The remedy is not state-wide, and (without checking) I don’t think there are provisions for such a thing. So a win would be Pyrrhic– you’d get one county revote for each county win, and I’ll bet there’s no way you could work that so you’d get enough counties overturned to make a difference in the ultimate result.
A second thing occurred to me describing this to an election lawyer: The affidavits I described (a voter saying that he or she voted with a present intent not to support the nominee in the general) might suffice for a prima facie case, but you can rest assured that Barbour’s lawyers (and probably those for the county executive committee) will object to their admission, that the voter must be called as a witness for cross-examination. So the challenger would have to subpoena each and every one to be sure this would work.
I don’t think so.
It seems to me reading between the lines that they may be trying to work up a simpler challenge: That almost 7K people voted in the run-off who voted in the Democratic primary. If they prove that, it would work, I guess, but I’m betting against there being that many. I guess he can throw in the inevitable voters who voted with some sort of mistake involved, but those are pretty serious work to identify.
If his challenge amounts to stomping his feet and claiming the Cochran campaign invited fraud but he doesn’t have to prove the extent to which it occurred, he is wasting everyone’s time and money pretty close to the point of sanctions, in my opinion.