It's not that the money is lost but is just re-allocated. The problem is that next year's budget (actually the year after's, I think) is based on what is spent the current year. If you don't spend it NOW, it doesn't 'roll over' and you don't get it approved in the future.

There IS no leftover money, there is just 'was ours, now somebody else's' money. Of course, the 'somebody elses' can scramble like hell to find something to spend it on.

Nice thought though.