There may be another hurdle for Barack Obama in that he’s running against a de facto incumbent, and many voters don’t even consider an alternative if they’re satisfied with the default choice (in this case, Hillary Clinton). I wrote about this phenomenon in CommonWealth in 2001, though the context was mayoral rather than presidential elections:

There is an alternative to the rational actor model for explaining all sorts of decision-making, including politics: “satisficing.” A hybrid of “satisfying” and “sufficing,” satisficing is the act of choosing the first, not necessarily the best, of the options that seem acceptable. A good-enough choice that is close at hand will always win out over any alternative that is more of a reach, even if it is superior.

…long-shot candidates … tend to run as what [author Stewart] Brand calls “interior designers”–those rare individuals who seek out optimal rather than makeshift solutions (and, in the non-metaphorical version of the profession, get paid handsomely for it). [Boston mayoral candidate Peggy] Davis-Mullen tried on this role in a July 19 speech, saying, “Our current mayor thinks that attending ribbon-cutting ceremonies is the same as discussing the issues with residents and focusing on neighborhood problems.” She promised to conduct a “needs assessment” and then draw up a specific development plan for each neighborhood–sounding very much like the decorator who comes up with a scheme for every room in the house when all you wanted was a couple of rugs that don’t get so dirty.

Interior-design candidates appeal to newspaper columnists and policy wonks … but they rarely win elections. As long as the incumbent has some concrete achievements he can point to (think of [Boston Mayor Tom] Menino’s Main Streets storefront improvements), voters seem to show little interest in someone who wants to start everything from scratch.