The US Supreme Court has ruled that Congress can restrict "soft money" contributions to political parties and restrict purchases of political advocacy advertising in the period immediately preceding an election. Meanwhile, the US Ninth Circuit Court of Appeals has declared that contributions to terrorist organizations are constitutionally protected, unless it has been proven beyond a reasonable doubt that the contributor knew of the recipient organization's terrorist activity.
The solution for campaign organizations is obvious: they should take their cue from foreign terrorist groups and establish a clandestine network of interlocking "charitable" and "political" organizations, with money being secretly funnelled from the former to the latter via elaborate money-laundering enterprises, preferably in foreign countries. A corporation can hardly be held responsible, after all, if its donation to the "World Regulation Relief Fund" results in an attack ad against a local congressman being purchased by a tangentially related foreign political organization--right?
I can think of no better way to clean up the financing of American campaigns. Thank goodness for the uncanny wisdom of the federal judiciary.