Under the proposed system, the candidates will have to raise funds on their own — and report every contribution of $ 1,000 or more within two days. (politico.com)
Like mentioned, brokers do report the contributions, so they can put two and two together to check for contributions if they want to do a full audit. (money.stackexchange.com)
In at least two instances, the Santa Clara County Democratic Central Committee United Democratic Campaign has accepted large checks from influential state labor unions, but failed to report those contributions in a timely manner. (calnewsroom.com)