I little research is making me very leery of the Greater Wisconsin Political Fund.
Their website has no “contact us” link, no names, no it solicits money but not volunteers, and the contact info they have is the same as the Greater Wisconsin Committee.
The Greater Wisconsin Committee is another shadowy organization, according to this article in Madison’s Isthmus newspaper:
The Fund seems to be the openly political arm of the Committee, though the committee claims non-partisanship.