First of all, I have to correct the inaccurate assumption that the Republicans want to cut taxes for the rich - we want to reduce taxes and reform the tax code for everyone. The Democrats oppose reform that would broaden the tax base, they'd rather borrow money.
The advantage would be for the rich. The federal government does comparatively little welfare, so it is not as if the increase in taxes upon the poor would have some compensation. The opportunities that arise from tax cuts to the super-rich would have to be offset by simply-incredible economic growth.
2006 -- because of a bungled war and the economic hardships that preceded the economic meltdown beginning in 2007.
On the other side, if the Republican nominee who wins in 2016 proves a disaster on military or diplomatic matters or gets caught in an economic meltdown, Democrats win a midterm that looks at first sight to offer few opportunities. 2020 then reverses the 2014 election and messes up R minorities in enough states. Democrats then gerrymander seats as the Republicans did in 2011.
Political fatigue?
