Scores of conservative donors have channeled more than $400-million since 1999 through a Virginia charity, Donors Trust, to anonymously support free-market, small-government efforts, according to the Center for Public Integrity.

The trust functions as a donor-advised fund to which clients can make tax-free contributions. The arrangement allows donors to keep their giving to libertarian and right-wing think tanks and media outlets private, especially “gifts funding sensitive or controversial issues,” according to the charity’s Web site.

The trust has received tens of millions from billionaire industrialist Charles Koch, the Searle Freedom Trust, and other conservative donors. In recent years it has increasingly focused on state-level efforts, for example providing almost all of financing for the Franklin Center for Government and Public Integrity, a nonprofit journalism organization that operates in several capitals.

Donors Trust is also a major supporter of organizations that dispute a human factor in climate change or oppose environmental regulations, giving more than 100 such groups $118-million in 2010, The Guardian writes.