The claim that the Citizens United decision allows payment of “money by corporations” and unions to politicians is a myth that liberals and campaign reformers continue to spew. Corporations and unions are prohibited from making campaign contributions to politicians by federal law, and that law has not been overturned by the Supreme Court (although some would argue that it should be overturned by Congress).
Citizens United held that the First Amendment prohibits Congress from censoring the political speech of any entity, and that includes independent expenditures that fund political speech. That decision is in the greatest traditions of liberty and free speech, the most fundamental principles upon which this country was founded.
A public funding program for all federal candidates for Congress and the presidency also would violate basic First Amendment associational protections. The high costs of modern congressional and presidential campaigns that are national in scope are such that they could be funded only through taxation. Voluntary contributions by Americans would never generate enough money for such a program, as demonstrated by the long-term decline in support for the current presidential public funding program — only eight percent of taxpayers check-off the line on their tax returns that contributes three dollars to the fund. It would violate the associational rights of individual Americans if the government were to force them through taxation to fund political candidates with whom those Americans disagree or do not support. The federal government does not have the power to force American citizens to fund the campaigns of political candidates any more than the government has the power to force them to vote for particular candidates.
The government also has no right to force television stations and other media outlets to provide free airtime for candidates. This is a clear taking of private property without compensation from owners, shareholders, and employees of those media entities.
The framers of the Constitution were right to protect political and other forms of speech from government censorship, since they understood from history that freedom of speech, as well as the right to associate and the ability to petition the government, are key anchors of liberty. For some reason, the OWS protestors despise these First Amendment rights, wanting to deny them to those with whom they disagree politically. You have to wonder what other constitutional rights they would try to eliminate as soon as they get rid of the First Amendment.