Ah yes, but you're thinking in terms of logical and term-based strategy. :) There's two flaws in that argument. Firstly, giving up power voluntarily is so extraordinary rare one can honestly say there is an institutional psychology to never give it up regardless of the circumstances (I think of one government in Costa Rica that voluntarily relinquished power). Secondly, an entire term is far too long in politics; even if the situation in the middle-east, the economy and the environment is seriously screwed in four years time, they wouldn't care. They just need to get 50%+1 on one particular day in four years time. Everything else can go to hell.