James Madison, in Federalist No. 10 addressed the possibility of a government controlled by "factions"—recognizing the dangers and likelihood of individuals gathering together to achieve a greater voice.  He could think of only two methods of removing the incentive:

1. "the one, by destroying the liberty which is essential to its existence;"
2. "the other, by giving to every citizen the same opinions, the same passions, and the same interests."

Madison believed that the Constitution would ensure that special interests could not seize control of the government nor use its power for their private benefit: "Society itself will be broken into so many parts, interests, and classes of citizens, that the rights of individuals, or of the minority, will be in little danger."  The competitive marketplace of ideas and interests is self-regulated. So long as all interests are free to compete, none will forever dominate. 

The DISCLOSE Act undermines the First Amendment by allowing only the voices of hand-picked, politically favored groups—such as labor unions—to be heard in national debates. This is not only a threat to the First Amendment, it is the exact sort of power-grabbing that Madison feared. It is entirely predictable that incumbents in power would want to limit free speech in order to retain their power, so predictable in fact that our Founders took precaution: "Congress shall make no law..."