The organisations, including the National Trust, the RSPB, Greenpeace and Friends of the Earth, have drawn up a Green Standard of six environmental commitments that they expect political parties to follow. The list covers issues such as climate change and green taxes.
The organisations will rate each party on how closely it meets the criteria, and will deliver their first verdicts at this autumn's party political conferences. Final assessments will be made public in the run-up to the next General Election.
Stephen Hale, director of the Green Alliance, one of the organisations responsible for the Green Standard, said an environmental beauty contest had broken out among politicians who were desperate to assert their environmental credentials but remained weak on action.
"The parties' rhetorical commitment is strong, so they are drawn into this," he said. "We are keen to set the terms of the beauty contest that has broken out and stretch their commitment."
Tony Burton, director of policy and strategy at the National Trust, said: "We want to ensure the political debate over the environment is determined by the public, not politicians."
To coincide with the launch of the new initiative, the organisations responsible released the details of a poll showing that 74 per cent of people said their voting intentions would be influenced by environmental issues.