There are three common themes in these races. The Democratic candidates are on their own, President Obama won't be campaigning in their state. The Democrats are under attack; the Koch brothers and their allies have already spent millions in negative ads and will continue to attack the President's record. As a consequence, the Republican candidates don't have a positive agenda; they're promising to oppose President Obama across the board.
It's class warfare. The 2014 midterm election pits the interests of the 1 percent against those of the 99 percent.