[T]his may well be an election cycle in which the small but real effects that campaigns and candidates can make could be decisive. You can think of a presidential election as a combination of objective factors (economic growth, perceptions of the performance of the president) that basically set the parameters of the election, yielding a small range of likely outcomes. In 2008, with the economy tanking, the entire range pointed to an out-party victory; in a year like 1996 or 1984, with the economy healthy, the entire range fell well within re-election for the incumbent. This may well be a year in which the range straddles wins for either side. That still doesn’t necessarily make silly-season nonsense — the one-day stories in the spring that are long forgotten by fall — any more important, but it can definitely mean that the real campaigning could very well make a difference. And that’s how it’s been for many months now.