[6] The League of Conservation Voters was founded by Marion Edey, then a young congressional staffer, who proposed a non-partisan, national pressure group for environmentalists "analogous to a political party" but endorsing Democrats and Republicans in a 1969 letter to David Brower, soon after he resigned from the Sierra Club.

[1][4][7] However, as it would have violated the Federal Corrupt Practices Act for LCV to be a subsidiary of a non-profit corporation like Friends of the Earth, Edey launched the organization as an independent political committee in 1970.

In 1972, they published environmental policy profiles of the leading presidential candidates and Rathlesberger edited an LCV Report, Nixon and the Environment (Village Voice Books, 1972).

[9] The related League of Conservation Voters Action Fund (LCVAF) financially supports political candidates, most of whom are members of the Democratic Party.

[12] LCV annually names a "Dirty Dozen", a list of politicians whom the group aims to defeat because of their voting records on conservation issues.

[14] In 2014, LCV and the Natural Resources Defense Council Action Fund launched LeadingGreen, a joint initiative to address climate change.

"[23] In 2002, Kimberley Strassel of The Wall Street Journal editorial board wrote that "Democratic politics...is what really drives the league's scorecard.

In an extremely partisan environment, Republican votes against environmental bills legitimate public opinion opposed to action on climate change.