Doesn't he get to keep whatever unused campaign contributions he has boodled up, too? If so, watch for the grease to hit those skids...
I'm not familiar with all the federal campaign fund rules and regulations....but generally speaking the money can be donated to a legitimate charity, to the campaign funds of other candidates, to the national party and probably to some other approved entities I'm not aware of.
It certainly can't be used by the "owner" of the fund to finance a vacation to the French Riviera, for example.
Leni