The New York Times reports on the tax-exempt organization of presidential candidate John Edwards, the Center for Promise and Opportunity. But it was his use of a tax-exempt organization to finance his travel and employ people connected to his past and current campaigns that went beyond what most other prospective candidates have done before pursuing national office. And according to experts on nonprofit foundations, Mr. Edwards pushed at the boundaries of how far such organizations can venture into the political realm. Such entities, which are regulated under Section 501C-4 of the tax code, can engage in advocacy but cannot make partisan political activities their primary purpose without risking loss of their tax-exempt status. Because the organization is not required to disclose its donors — and the campaign declined to do so — it is not clear whether those who gave money to it did so understanding that they were supporting Mr. Edwards's political viability as much or more than they were giving money to combat poverty.