Dozens of activists from nine groups kicked off a 40-day countdown to Earth Day on Thursday, vowing that this year's environmental celebration would be more political than in years past.

The groups representing war veterans, religious communities, and business leaders said they would take action to get Congress to pass a climate change and clean energy bill. They called their advocacy push an "Earth Day Revolution."

"For our generation, this is a battle for our existence," Reverend Lennox Yearwood, Jr., head of the Hip Hop Caucus, said at a press conference on Capitol Hill Thursday.

Representatives from the Truman National Security Project, Environment America, League of Conservation Voters, Sierra Club, Rock the Vote, and National Association for the Advancement of Colored People also spoke.

In the weeks leading up to Earth Day, they are planning to hold rallies in 20 states, lobby Senators, and provide daily reasons to support their cause at www.earthdayrevolution.com . Several other groups signed on to a letter demanding action from the Senate.

Michael Oko, a spokesman for the Natural Resources Defense Council, hesitated to call the April 22 holiday a deadline for the lawmakers but said they should act soon.

The activists in the crowd included Gwen Dobbs, who came dressed up as a polar bear.

Dobbs, a staff member of the Alaska Wilderness League, said the outfit gets people to think about the effects of climate change on Alaska.

-- Ambreen Ali, Congress.org