If Obama gives construction of the oil-sands pipeline a green light this spring or summer, he could frame it as an example of his support for North American energy production, a boost for the economy, and a helpful concession to vulnerable Senate Democrats who support the $5.4 billion project.

But he could go the other way. A flat-out rejection of the pipeline might enthuse the Democratic base for the midterm elections in November, which will hinge on turnout.

The third option: Punt a decision again. A delay until after the midterms might be safest for the president because it would excite only mild criticism compared to the storm of opprobrium that would follow a firm decision either way.

Delay could also make Keystone a bargaining chip for the president in either the lame-duck session of Congress or next year, when he could face a Republican House and Senate.