Worries over climate change pushed tens of thousands of protesters from all over the United States to Washington in sub-freezing weather Sunday to deliver their message to the White House, DPA reported.
At the top of their list of concerns is the much-debated 2,700-kilometre-long project, known as the Keystone XL pipeline, that would transport tar sands oil from Canada across the centre of the US to the Gulf of Mexico for refinement.
While Obama has rejected part of the project, saying he needs more time for review, the southern leg has already been approved by the US Army Corps of Engineers, USA Today newspaper reported.
Demonstrators carried signs saying "Lifeline, not Pipeline" and held up miniature wind mills that represented alternative energy.
"I would say be brave and stand up against the oil interests that are not in our national interest," was the message for Obama that one woman demonstrator gave CNN.
Organizers, who said the crowd of 40,000 was the largest climate change demonstration ever in the US, called for Obama to make good on his promises about lowering carbon emissions that are blamed for global warming.
Michael Brune of the Sierra Club said that Obama "holds in his hand" the power to push forward the change from fossil fuel to clean energy.
In his annual State of the Union speech on Tuesday, Obama proclaimed his accomplishments - production of more oil in the US than in 15 years; doubling of the distance cars will go on a litre of gas; and more alternative energy generation such as wind and solar.
He noted however that "the 12 hottest years on record have all come in the last 15" and outlined a number of measures to promote clean energy.
"We can choose to believe that Superstorm Sandy, and the most severe drought in decades, and the worst wildfires some states have ever seen were all just a freak coincidence," Obama said. "Or we can choose to believe in the overwhelming judgement of science - and act before it's too late."
Resistance in Congress to a carbon-trading scheme as well as the powerful oil industry lobby have blocked any far reaching alternative energy measures.
And even Obama hedged on his pro-clean-energy avowal in November, saying it would involve some "tough political choices" amid the stagnant economic recovery.
"Understandably, I think the American people right now have been so focused and will continue to be focused on our economy and jobs and growth that ... if the message is somehow we're going to ignore jobs and growth simply to address climate change, I don't think anybody's going to go for that," he said in the broadcast interview.
"I won't go for that," he said.
Obama was not in town to see the climate change demonstration. He was in Florida over the long holiday weekend taking golf lessons from Tiger Woods.