There are a lot of things that contributed to this. ‘Nation building’ might be one if you want to call it that. Certainly a prolonged Iraq War contributed to 2006, and to 2008 to a lesser extent. The economic crisis probably is pretty high on the list since neither Bush, McCain or anyone else seemed to want to defend the economic record of the six years of growth before that, and refused to refute the argument that deregulation and tax cuts caused it. The GOP tried to go populist and point fingers at Wall Street instead of pointing towards the other end of Pennsylvania Avenue.