The pipeline is designed to carry about 830,000 barrels a day from Alberta and shale rock formations in the U.S. along a route that would traverse six Great Plains states. The administration has previously given approval for the pipeline’s southern leg to relieve an oil glut in Cushing, Oklahoma.

Environmentalists view Keystone as a test of Obama’s sincerity about making climate change a priority in his second term after failing to advance legislation to cap greenhouse gases, which scientists say causes global warming, in his first.

“We will respond to the threat of climate change, knowing that the failure to do so would betray our children and future generations,” Obama said in his second inaugural address. “That is how we will preserve our planet, commanded to our care by God.”

During the fundraiser at Steyer’s home he offered a more restrained approach: “The politics of this are tough” because of the struggling economy, he said. Democrats must show middle- class voters “we’re working just as hard for them as we are for our environmental agenda,” Obama said.

Much like the fallout from the pipeline itself, the political facts of approval or rejection are far from clear. While Keystone is largely popular, the depth of support isn’t great.

“It has a much stronger emotional reaction for those that oppose it,” said Bill Burton, a former White House adviser who is leading a coalition opposing the pipeline. Burton, who helped raise $65 million for Obama’s re-election, said the campaign he started this month, the “All Risk, No Reward Coalition,” is mostly aimed at Democratic donors and activists.

2012 Campaign

A report by the League of Conservation Voters, which also opposes Keystone, found that none of the candidates targeted in 2012 for their opposition to the pipeline lost their election.

The Pew survey of 1,501 adults was conducted March 13-17, before an Exxon Mobil Corp. pipeline burst in Arkansas, spewing the same kind of mixed oil sands onto the streets of a sleepy suburban neighborhood.

Carroll Doherty, associate director of the Pew Research Center for the People & the Press, said “things like the Arkansas spill have the potential” to change public opinion. At the same time, Doherty said, public opposition based on a single event can be short-lived, especially when economic concerns are high.