The Wall Street Journal identified 326 donors who hosted fundraisers this year for Mr. Bush’s super PAC, based on invitations and news reports compiled by the Sunlight Foundation, a nonpartisan government watchdog.

One in five were either members of the “Team 100,” those who raised at least $100,000 for the Republican National Committee during George H.W. Bush’s 1988 presidential campaign—or “Pioneers” or “Rangers,” who collected at least $100,000 or $200,000 for George W. Bush’s national campaigns.

Nearly a quarter worked in at least one of the Bush White Houses or received a presidential appointment; 24 were tapped by Mr. Bush’s father or brother to serve as ambassadors; 46 worked in Mr. Bush’s administration in Florida or were appointed to advisory boards. A number of donors belong to more than one of these categories.

Mr. Bush’s top allies include 11 billionaires, six former and current owners of professional sports teams and former Vice President Dan Quayle. There is an internationally competitive sailor, a former chairman of the U.S. Export-Import Bank, as well as the author of “Nice Guys Finish Rich: The Secrets of a Super Salesman.”