What happens to unused political campaign money at the end of a race?

donations and funding that come from "private" sources and are left over can be put in a "war chest" for future campaigns. they can donate it to other candidates, pay off bills from an earlier campaign..or donate it to charity. they are NOT supposed to spend it on themselves. you'd think that the moral and right thing to do with the money would be to donate it to charities or relief funds (katrina etc.) but i bet at least 80% goes back to the political party or another candidate. if the money came from federal sources, it must be returned to the Treasury.