The economy has been staggering, with stagnant or no growth, for several years after a financial crisis. Loud voices are being raised against Wall Street financiers and the concentration of great wealth in few hands. Rapid technological development is generating massive economic change, with many old-line jobs vanishing. Majorities disapprove of the Democratic president, as they had of his Republican predecessor.

All this is happening after a protracted period of partisan polarization and political deadlock between roughly equal-sized Democratic and Republican parties. The polarization is all the more bitter because it is based on vastly different outlooks on cultural issues.