* Free speech
* Private property
* Preventing small interest groups from having outsized influence
Choose two. Or maybe 2.5 at the most. But the problem is there's no clear delineation between "money" and "speech". At some point you either impose restrictions on free speech, prevent the unlimited accumulation of wealth, or accept that billionaires are just always going to have more political influence than Joe Sixpack.
For as much as people like to shit on it, very few people have actually read the body of Citizens United. If you haven't, I highly suggest doing so. Because it really brings up deep paradoxes that suggest that the First Amendment is fundamentally incompatible with campaign finance restrictions. European countries manage to keep money out of politics, simply by not sharing America's Constitutional guarantee of absolute free speech.
There's no logically consistent way to regulate "money in politics" in a way that doesn't also restrict "speech in politics". Consider all of the below scenarios and tell me at what point "money" ends and "speech" begins:
* A wealthy person makes huge campaign donations to his favored candidate.
* A wealthy person runs for office, and uses his personal wealth to buy campaign ads.
* A wealthy person buys a media conglomerate, and uses his editorial control to favor his preferred positions.
* A wealthy person buys a media conglomerate, doesn't exert direct editorial control, but only hires journalists who share his opinion.
* A wealthy person uses his money to fund movies with no political message. However he becomes famous from starring in his own subsidized movies. He uses his fame to spread his message without directly buying access.
* A wealthy person hires people to attend protests in favor of his position.
* A wealthy person finds people who genuinely wants to attend his protests, but subsidizes their transportation, signs, organization, etc.
* A wealthy person buys nice clothes and speaking lessons for people that share his positions so they become more persuasive.
* A wealthy person buys a chain of sports bars and makes sure that the TVs only play his preferred cable news channel.
* A wealthy person biases hiring to favor like-minded people. On net that raises the status and influence of people like him.
* A wealthy person biases his firm to doing business with firms run by ideologically like-minded CEOs. That makes people who share his views wealthier, and hence gives them more influence.
* A wealthy person is unbiased when hiring, but locates all his offices in areas that share his views so that hiring naturally biases towards like-minded people.
* A wealthy person uses his money to attract a very famous and attractive movie star. Once married he influences her to his political positions, then that movie star uses her famous and status to influence her fans.
* A wealthy person uses his money to throw big, fancy parties. He invites anyone regardless of views. However at the beginning of the party, when people are enjoying the free cocktails and hours d'oevrues his always gives a toast that gently nudges the partygoers in favor of his views.