The United States of America is supposed to be a democratic republic with a system of government emphasizing basic democratic values. That each individual citizen has an equal say in choosing governmental representation is essential to the democratic nature of a democratic republic. Additionally, certain individuals outside of the government should not have disproportionate influence on governmental policy that effects everyone. Each person should have equal influence as governmental policy should act for the greater good of everyone, not favored individuals.
All of these factors are foundational to the argument for campaign finance reform. The fact that significant efforts to reform campaign finance regulations have been undertaken repeatedly in our government is alone indicative of the merit of the argument. Theodore Roosevelt asserted that "contributions by corporations to any political committee or for any political purpose should be forbidden by law." Congress passed the Bipartisan Campaign Reform Act of 2002 to eliminate unregulated ‘soft money’ contributions.
When our political campaigns are funded by an array of private individuals (often effectively representing certain interests or organizations) that unfortunately serves to work against the two values establish above. In that a richer campaign is a more successful one (while not necessarily true, if money is spent reasonably well then a campaign with more economic resources will be better equipped to swing public opinion in favor of its candidate), those candidates that are backed by individuals with more money to give will have a better chance of winning (or of increasing his or her odds). In that sense, those with more money have more say in who is elected for a given office than those with less money. Likewise, because candidates with more donations do better, elected candidates are automatically indebted to those hugh campaign contributors that may represent special interests. In that sense, those who do give more money can subtly have a greater influence on the policy decisions of a candidate after he or she takes office.
The “limits” placed on campaign finance by laws that are already in place are relatively insignificant – the people running these campaigns find loopholes for a living. In order to level the playing field when it comes to political campaigns and democratic government, campaign reform in which no individual can donate more many than another would be necessary. Two Yale professors, Ackerman and Ayres, proposed a plan under which every voter would be given $50 to donate to candidates (broken down into $10, $15, and $25 chunks to donate to House, Senate, and Presidential candidates respectively, in whatever way he or she wants to). Furthermore, all contributions would be entirely confidential. Unless you saw a given voter check the box or fill out the form, there would be no way to track who donated to whom. Unfortunately, Ackerman and Ayres plan still leaves plenty of room for private donations under the condition that they are entirely confidential and processed through the FEC (Federal Election Commission) so that a candidate would truly have no way of really knowing where the money was coming from. This seems to leave room for richer individuals with special interests to give more money to a candidate representing their interests than a poorer individuals to give to a candidate representing their interests which is still reflective of inequality in political clout. By removing the weight of private donations a relatively foolproof system could be formed. Such a plan would eliminate the inherent inequalities that result from campaign financing as we know it and lead to campaigning and government that serves everyone in the country better and more equally.
This site has some good background information on the history of campaign finance reform.
This site outlines and persuasively discusses the details of Ackerman and Ayres.