One donation in that category [more than $50K] came from an elected Republican official who insisted on remaining anonymous, even to Mr. McCain, Mr. Davis said.
http://www.nytimes.com/2005/03/08/politics/08mccain.html?pagewanted=2&ei=5090&en=6f5a7b42d9b923af&ex=1267938000&partner=rssuserland
So what Republican elected official would donate personally to this Institute, yet not wish to be revealed to even McCain himself? Politicians who donate to each others' PACs typically do so for the chits they run up.
(snip)
Donors said the institute had become more aggressive in recent months in its push for money. Though it is not required to do so, the institute lists all its donors on its Web site. This year, the organization began breaking them down by ranges of contributions, which showed the vast majority of its hundreds of contributors gave $500 or less. About 40 gave between $500 and $5,000, 8 gave up to $50,000 and 12 contributed above that level.
One donation in that category came from an elected Republican official who insisted on remaining anonymous, even to Mr. McCain, Mr. Davis said. Some donors, though, are communications industry giants who had business before the Commerce Committee when Mr. McCain was its chairman. Echosphere, a communications company started by Charles Ergen, a founder of EchoStar Communications and the DISH Network, gave $50,000 or more to the institute. So did CSC Holdings, a subsidiary of the Cablevisions Systems Corporation, headed by Charles F. Dolan, and the Chartwell Foundation, the charitable group funded by A. Jerrold Perenchio, the Univision billionaire.
Mr. Davis and Mr. McCain, who is not currently raising money for his own political purposes, said they saw no problem in accepting donations of that magnitude from foundations associated with people and companies with interests on Capitol Hill.