There has been a big push, particularly during the last election cycle, for private donor lists to private PAC groups to be made public. Why?
What is the IRS currently under investigation for doing? They are under investigation for using their authority to target political opponents of the administration. From major donors to the Romney campaign to political PACs to competitor companies of major Democrat donors to groups that support activities that the State Department opposes, the IRS was used to target these groups and individuals. The effect of this is to try to silence political opposition, to get people and groups to sit down and be quiet.
If the donor lists of private groups would be made public, what would stop the government from using the IRS to target those donors? Absolutely nothing. In fact, the administration has argued that nothing they did was illegal.
Do you want the government to have that kind of power? If you think it's ok, did you defend Bush when he was accused of the same thing? Would you be ok with a President Dick Cheney targeting his political opponents?
I don't know about you, but I don't want any government to have that power, regardless of what party is in charge.