Elections are not rocket science, nor are they magic. Most are won or lost--by both sides at all levels of the ballot--for the same reasons they have always been won or lost. And, those reasons are usually right in front of our faces--as much as, pundits, politicians, staff and Facebook armchair cynics would like to make it into something much sexier and unprecedented.It's absolutely true. Which means that while certain actions of candidates, spokesmen, operatives, staffers, pundits, volunteers, may lead to specific reactions by and large there is no narrative lynchpin that makes one campaign so much as unique and special as to be exceptional in a historical narrative.
You do what you can, or don't do, and if it is enough, correct, sufficient, or proper, you win. On the other hand, you lose.
Which makes it horrible to say, but if it is not one thing, it is another. You can list a specific quote and indicate how it alienated a specific voting bloc but the simple category is "the candidate said something stupid and potential voters responded".
What it means for the activist or the volunteer or even the paid operative (let alone consultants and lobbyists) is that there are very few situations that are absolutely so unique that one cannot predict events and determine correct courses of action. At the same time it means that elections cannot simply be crafted and formulated by introducing the correct factors, variables, and substituting "Smith" and "Jones" for "candidate" and "Conservative" or "Liberal" for "ideology".
I wish it was magic. Although if it was Christine O'Donnell would have had her Delaware Senator race in the bag just by sacrificing a virgin and a black cat.