Private foundations have such a requirement already, and while college officials argue that foundations are expressly designed to spend their endowments, and colleges use theirs to support the institutions for the long haul, the idea of applying it to colleges is gaining currency as their endowment coffers swell. Last month, an annual survey by the National Association of College and University Business Officers showed that 76 college endowments now exceed $1 billion, up from 39 in 2004.

Colleges and universities also benefit from huge direct investment of federal funds, especially in the form of financial aid and research grants, and tax breaks (state and federal) that allow them to use tax-free bonds to build facilities and take in many kinds of revenues (including donations) without taxation to them or their donors.