It’s not against federal law to have unpaid, enthusiastic volunteers making signs, donating their time and money, working the grounds, and contributing individually without the aide of special-interest groups or PACs, but whatever. It’s all moot anyway, right? Paul’s not going to win anyway, he’s a moonbat kook. Let’s just say that all of Ron Paul’s money came from Code Pink, MoveOn.org, and neo-Nazis skinheads and kill the thread.
Note the bold. Who are they donating to? The campaign? Within legal limits that's fine and hardly worth explaining.
Cash contributions to non special-interest groups or PACs, I haven't a clue what those are, but if they're advocating the election of a specific candidate, I'm consult an attorney before I became involved.