It is hampered by its very design. The agency was born of embarrassment, at a time when exposure of slush funds, corporate donations and payoffs in the Nixon administration had cast a pall over the whole federal government. But, while creating the illusion of reform, Congress made the FEC too weak to enforce the law. The agency can't conduct random audits or issue injunctions to stop violations in progress. Starting even a small investigation requires the votes of four of the FEC's six commissioners, as does every step in an inquiry.
Defendants can appeal at every turn.
The letter came nearly three years after Bush left office. For any campaign, there is an incentive to drag out the process. After all, even if a fine is levied, the infraction will seem like a distant memory to the public. And candidates know that the watchdog has only gums. And members like it that way.