Would they? As far as I know, there are heaps of loopholes in all these laws. Ones which powerful guys with skillful lawyers will always be able to exploit. I'm sure they'll find a way to present it as if someone else is raising money "totally independent" of this guy's candidacy, just because they "like him very much". And the shit will fly on.

Don't get me wrong, I'm all for getting money out of politics. But placing arbitrary limits to money in politics doesn't fundamentally address the problem. Forcing full disclosure and transparency onto political campaigns seems a more adequate measure to me. Fine, let them spend huge amounts of money on campaigning. But make the origin of every dollar be known to the public. Then the public will be able to take their informed decisions.