Every vote counts. Democrats have blocked a proposed expansion of the U.S.-Canadian oil pipeline by a margin of a single vote. This puts to rest — however briefly — a political struggle between Republicans arguing for job creation and environmentalists concerned about the project’s carbon emissions. President Obama, who’s been hesitant about the project, is likely to face a renewed push in January by a Republican-led Senate. But that doesn’t mean he’ll be reaching for his pen to sign it into law.