My money is on McCain or Hillary/Bill.
Maybe it was paid for by The Clinton Foundation?
The Booshes will be shocked to find out sister Hillary or John McCain have done anything wrong, of course.
If it was paid for originally by a Republican never-Trumper, my money is on Jeb!, McCain, or Sasse. All culprits devoted to maintaining the status quo. Since McCain admitted to delivering the document to the FBI, my money is on him. It also might explain why McCain has gone into virulent overdrive recently.