Rather than a petition to remove the tax - free status of the humane society which will still leave PETA to continue on. Would there be a way to convince the senators and congress to make a brand new regulation that would in this economy where the government needs lots of revenue. Get them to create a regulation for non-profit or tax- free organizations whereas they must pay regular taxes unless at a minimum of 50% of their donations goes into the cause their charity represents. For example HSUS, PETA, SPCA all say they do animal care well if 50 % of the donations raised for the year was not used for direct animal care thay get the full tax burden.
This will have no effect on real charities as they already use most of their contributions for their charitable purpose.
PS: wages do not count.
This would do the same thing but get them all in one go.