I think a problem a lot of harder conservative and Tea Party folks don’t have a grip on is that most people likely to vote for Republicans get alienated because while they agree with conservative principles, they derive some benefit from the status quo (government handouts for a developmentally disabled child in the family, for example) and when push comes to shove, they like it.
As long as they’re selling what people aren’t buying, when it comes to a vote, they will consistently (but not exclusively) a buck short.
This, however, isn’t a case of Cochran getting or not getting so-called moderate or centrist votes. He won with votes from rats, which he won’t be getting in the GE, and he won’t be getting conservative votes. How does he win? Not with my vote, for sure.