Keystone XL Pipeline: to build or not to build?

US President Barack Obama currently faces the biggest test of his green credentials. The administration is hesitating over whether to give the green light to the construction of the huge Keystone XL pipeline. If built, the pipeline would transfer 800,000 barrels of tar sands oil per day from Canada to Texas and the Gulf of Mexico. Will Obama side with the green lobby or with those demanding jobs and increased energy independence?