Both groups call themselves nonpartisan and are incorporated as tax-exempt charitable organizations. But the council, a New York-based alliance of 35 Christian denominations, is deeply involved in liberal social causes, such as reducing poverty and making peace; it achieved a long-standing legislative goal yesterday when the House voted to increase the minimum wage.

The institute, a Washington-based think tank, is allied with conservative groups on issues such as same-sex marriage. From its founding in 1981, its primary effort has been to challenge what it calls the "leftist" political positions of mainline Protestant denominations, such as the United Methodist Church and the Presbyterian Church (U.S.A.). It has worked closely with conservatives in those denominations, including Episcopalians who have broken away from their church since it consecrated a gay bishop in 2003.

Yesterday, the institute released a 90-page report, titled "Strange Yokefellows: The National Council of Churches and Its Growing Non-Church Constituency." It argued that the council in recent years has faced diminishing contributions from its member churches and has made up the shortfall with grants from such "left-leaning" groups as the National Religious Partnership for the Environment, the Ford Foundation and the Sierra Club.

In the fiscal year ending June 2005, the council received $1.76 million from secular foundations and non-church groups, surpassing the $1.75 million it received from member churches and "signaling a radical new development in the council's history," the report said. Noting that the enrolled membership in mainline Protestant denominations has fallen from 17 percent of the U.S. population in 1950 to 7 percent, it said that only six of the council's top 16 funders today are church groups.

"Several of these [non-church] groups that the NCC has turned to for financial and other forms of support are so blatantly partisan that they can be accurately described as . . . the shadow Democratic Party," the report's main researcher, John Lomperis, told reporters.

His co-author, Alan Wisdom, added that the council has abandoned the goal for which it was founded in 1950 -- fostering "Christian unity" -- and does not represent the true views of the 45 million Christians in its member churches, which include several historically black denominations and Orthodox churches.

The first question at the institute's news conference on the report came from the Rev. Leslie Tune, a staff member of the council, who asked where the institute gets its own funds.

James Tonkowich, the institute's president, said that about 60 percent of its roughly $1 million in annual revenue comes from individual donors and about 40 percent from conservative foundations, such as the Scaife, Bradley, Coors and Smith Richardson family charities.

Tonkowich also acknowledged that his organization has made public less information about its funders than the NCC has.

In separate interviews, Lomperis and Wisdom said they wrote the report largely in response to earlier criticism of the institute's funding from the council's general secretary, the Rev. Bob Edgar, a former Democratic congressman from Pennsylvania who is also a Methodist minister. In his 2006 book, "Middle Church," Edgar wrote that the institute's fundraising list "reads like a Who's Who of contemporary conservatism."

Edgar's book was the latest of several articles and books by liberal Protestants accusing the institute of fomenting divisions in their churches. In an article posted last year on the Web site of the Episcopal Diocese of Washington, the diocese's spokesman, Jim Naughton, said the IRD has received at least $4.6 million from conservative foundations since 1985, allowing the institute and a "small network" of fellow conservatives "to mount a global campaign that has destabilized the Episcopal Church."

Edgar, 63, who is stepping down as head of the NCC at the end of the year, did not speak at the institute's news conference. But he stayed afterward to shake hands with the report's authors and to thank them for recognizing that he has turned around the finances of the council, which was running a $5.9 million deficit when he took over in 2000 and has now balanced its budget for five years in a row.

"I was brought in to do three things: raise money, raise money and raise money," he said. "Thank you for highlighting that secular as well as religious organizations now recognize the importance of the National Council of Churches."

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