Disclosing Grassroots Lobbying

Just catching up on political movements in teh House and Senate, and found out about Senate Bill 2128 (A bill to provide greater transparency with respect to lobbying activities, and for other purposes). This bill – introduced by Senator John McCain – would require grassroots lobbying expenditures in excess of $25,000 to be disclosed.  I wonder why conservative (and I'm sure some non-conservative) organizations are having a fit about this.  Frankly, I think if a charitable organization has more than $25,000 to spend on this kind of thing, then I don't think it unreasonable to ask for a disclosure.