His reelection campaign used Earth Day to announce the relaunch of "Environmentalists for Obama," a mobilization effort that was also part of the 2008 campaign.
The video message from Obama touts administration policies on green energy development, fuel efficiency, conservation and other matters.
The president's reelection campaign may nonetheless be challenged to replicate the mobilization of environmentalists that occurred in 2008.
Environmentalists have cheered many White House policies, such as tougher auto mileage standards; first-ever climate change rules; regulations to cut smog-forming and toxic emissions from coal plants; and renewable energy programs in the 2009 stimulus law.
But Obama's first term has also seen its share of tensions with activists. The White House has made some decisions that green groups say are bad for the environment.