Obama sought in November to delay a final verdict on the pipeline until after the 2012 election by calling for review of alternative routes around the environmentally sensitive Sand Hills region of Nebraska. The move delayed a decision on the project until 2013 to give the administration time to conduct additional review of the new route.
But Republicans secured inclusion of a measure in the two-month payroll tax cut extension package that would force Obama to make a decision on the pipeline project within 60 days.
Obama administration officials have said they will have no choice but to reject Keystone because the expedited timeline pushed by Republicans would not leave enough time to conduct the necessary review.
But the GOP is nonetheless pressuring the administration to approve the project, arguing it will boost the ailing economy.