I think Hillary Clinton said once that you campaign in poetry, but you govern in prose.
I don't think Obama's a bad p********, but he's been given a terrible job. GFC, Iraq, Afghanistan, CO2 emissions, health care, education, national deficit... the expectations that were placed on him were sky high, and people actually believed he could deliver on everything. America's pretty much ungovernable - the Founding Fathers went out of their way to dilute power, and it takes remarkable circumstances to galvanise the disparate branches of government into a cohesive whole.
Obama's mistake was to inspire the people to imagine a government which wasn't stocked with partisan, self-serving politicians. And to appeal to said politicians' better selves.