The last time campaign finance reform was on the agenda, the conservative position was that spending limits of any kind were wrong. Disclosure was the answer. Disclose who's giving money to what groups, and the public will be able to sort out truth from fiction.
Now, I think this was a highly idealistic view that dramaticalloy overrated the public's ability and willingness to sort through complex information. But there is some value in disclosure. Now that campaign finance reformers want to force huge donors to disclose their political activities, the conservative position is now that disclosure is unfair. Here's GOP pooh-bah Ed Gillespie:
[I]f you look at the history of donors on the right giving to a certain causes or organizations, they have been subject to some pretty vicious attacks from the organized left. People who gave to a referendum out in California were flooded with emails pretty nasty in nature and had their jobs threatened. You saw what happened with Target who supported a candidate for governor in Minnesota and then all of the sudden the organized left went after Target.
And the fact is, a lot of these folks who are opposed to more government control in our economy and more government intervention in our economy are already to subject to a great deal of government control and regulation in our economy. And there is fear of retribution. There is a fear that well, if I give to this organization, those who are in control and power and who seek to further government control might give my sector or my company or my own personal lives, they might come after me.
In other words, if you disclose political activity, people might... respond! They could decide not to buy products from a certain corporation. Or send them unfriendly emails. Heaven forbid! Gillespie also raises the prospect that the government could single out companies for retribution, but unlike his examples of consumer blowback, he has no anecdotes to fall back on, because the fear is entirely hypothetical.
In any case, look for many years worth of conservative arguments about disclosure to fall down the memory hole.