The New York Times quotes Professor Nate Persily on how the Supreme Court decision in Citizens United may contribute to increased political polarization. 

The five-member conservative majority of the Supreme Court did Democrats and reformers a favor when it released its decision in Citizens United in 2010.
The ruling and its progeny, much reviled by the left, effectively banned limits on political contributions and opened the door to direct corporate financing of campaigns. In doing so, Citizens United inadvertently rescued progressive crusaders from their futile, century-long struggle to control the flow of money into politics.

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Nate Persily, a Stanford law professor and the editor of the recently published book, “Solutions to Political Polarization in America,” observed in an email, “I generally support most public funding programs and support this one as well.”

Persily raised the possibility, however, that legislation boosting the role of small donors could increase polarization because there is evidence that such donors are “more ideologically motivated” than others. To counter the potential of increased polarization, Persily said that public funding could be expanded to “cut very large checks to the political parties to spend as they wish,” since the parties tend to be moderating forces.