WASHINGTON — The conservative-leaning Hoover Institution, based in California, and the liberal Center for American Progress, based in Washington, are polar opposites in terms of political leanings. But according to a first-of-its-kind survey of the world’s most prominent research organizations, the institutions share an important trait: a relatively poor record of disclosing the sources of their financing.

The two organizations, along with other major players in Washington such as the Center for Strategic and International Studies and the Hudson Institute, each earned just one star out of a possible five in the survey, to be made public on Wednesday, an advance copy of which was provided to The New York Times.

The survey, conducted by a small nonprofit group called Transparify, has already caused major ripples in the think tank world, even before its official release.

Major research organizations around the world — including at least half a dozen in the United States like the Washington-based Stimson Center, which focuses on foreign policy, and the Center for Global Development, which combats poverty worldwide — have taken steps in recent months to avoid a poor ranking by disclosing more information about their funding sources on their websites.