What the Keystone XL pipeline means for Obama's legacy Washington - The Senate is scheduled to vote on the controversial Keystone XL pipeline project Tuesday. If it passes - and that's still in doubt - the bill will go to President Obama's desk. He has signaled he is likely to veto it. That pushes the whole issue into next year and the new Congress, where Republicans will control both chambers. The political reality of Mr. Obama's final two years in office will be in place. And the most important numbers will be 67 and 290 - the number of votes needed in the Senate and House, respectively, to overturn a presidential veto. But let's take a step back and look at just how important - or not - Keystone is to Obama's legacy. Big picture, the economy and health care reform are his most important legacy issues. Immigration probably comes next, especially if he takes executive action to defer deportations, as promised. Then there's climate change. The pipeline project, partially completed and awaiting US approval of the final leg for six years, would carry tar-sands oil from Canada to the Texas Gulf Coast. Even to environmentalists, a key part of the Democratic base, the project has taken on symbolic importance - perhaps going beyond its actual impact on greenhouse gas emissions. "The Keystone XL pipeline has become a symbol of how misguided the energy debate is in Congress, and how desperate oil companies are to go after resources that are dirtier, more dangerous, and more expensive to extract," says Michelle Robinson, director of the Clean Vehicles Program at the Union of Concerned Scientists, in a statement Monday. Environmentalists will see Obama's final decision on Keystone as a signal of how serious he is about climate change. His agreement with China last week on reducing carbon emissions, seen as a historic first step for the world's top two polluters, would lose some of its shine if he turned around and approved Keystone. The Democratic donor base is also looking at how the party goes on Keystone, first among them billionaire anti-Keystone activist Tom Steyer. Obama may be a lame duck, but he's still the leader of the Democratic Party. Weighing in favor of approving the pipeline is the labor movement, which has its own divisions over Keystone, but is another important element of the Democratic base. AFL-CIO President Richard Trumka has called on Congress to approve the pipeline, citing jobs and the economy. Weighing against is top adviser John Podesta, the architect of the US-China climate agreement. When Mr. Podesta joined the White House at the beginning of the year, he said he would steer clear of the Keystone issue. But it's hard to imagine his presence and his views haven't had an impact. Podesta's one-year appointment ends soon, at which point he is expected to play a top role in Hillary Rodham Clinton's presidential bid. The DNA of Obama's climate and energy policy will head straight into the campaign of the Democrats" top prospect for 2016. For now, Obama can avoid a public decision by saying he's waiting for the State Department to issue its final recommendation and for the Nebraska Supreme Court to rule on a case involving the pipeline's route. That ruling is expected in January. Obama has a third argument available that would allow him to avoid opining on the pipeline's merits: When and if Congress passes pro-Keystone legislation, Obama can wield his veto pen and say that he rejects legislative involvement in the decision. The president is clearly a big believer in executive-branch power. Still, sooner or later, Obama will probably have to go public with a final verdict on Keystone. His only out would be for Congress to override a veto, green-lighting the completion of the pipeline without the president's blessing. But if Obama wants a clear legacy on energy and climate-change policy, he may feel compelled to say something.