Top and bottom against the middle is the oldest coalition in politics. Throughout history, the aristocracy has always hated the middle class. Solid burghers are prickly, jealous of their rights, too self-sufficient to be threatened, and too proud to be bought off. Elites far prefer the lower class, which can be more easily manipulated. 

The top and bottom coalition usually aligns with the left, with its rich potential for cronyism and clientelism. Only the squeezed middle actually believes in economic conservatism, with its free markets and sound budgets.