For President Obama, approving the Keystone XL Pipeline should have been a no-brainer. All the State Department had to do was conclude the obvious – the pipeline is in the U.S. national interest.

What other reasonable conclusion is possible? Building the 1,700-mile, shovel-ready project would create thousands of construction jobs, stimulate tens of billions of dollars in business spending, and generate billions of dollars in tax revenues. Once operational, the pipeline would enhance U.S. energy security, displacing oil imported from unsavory regimes with up to 830,000 barrels a day of tar sands oil from friendly, stable, environmentally fastidious, democratic Canada. Canada already ships us more oil than all Persian Gulf states combined, and Keystone would significantly expand our self-reliance on North American energy.

Obama had only two policy choices. He could either disapprove the pipeline on the grounds that environmental concerns over incremental greenhouse gas emissions and oil spill risk outweigh the substantial economic, fiscal, and energy security benefits of the pipeline. Or he could approve the pipeline on the grounds that its benefits outweigh potential environmental impacts.

He did neither. Instead, he punted a final decision until after the November 2012 elections. The timing of Obama’s decision not to decide – just days after 10,000 anti-Keystone activists formed a protest circle around the White House – strongly suggests that Obama’s waffle was politically-motivated.

If Obama approves the pipeline, he risks alienating the green wing of his political base. ”Sierra Club executive director Michael Brune told reporters recently that Obama’s decision on the pipeline would ‘have a very big impact’ on how the nation’s largest environmental group funnels resources toward congressional races rather than the race for the White House,” Politico reported last week. A constant theme of protest rallies since August is that Keystone is a “litmus test“ for Obama. As one green blogger put it, “if the president cannot stand with the environmental community against the pipeline, some say, why should they stand with him at all?”

If, on the other hand, Obama disapproves the pipeline, he risks alienating union labor, such as the AFL-CIO-affiliated United Association of Plumbers and Pipe Fitters. In addition, disapproval would make candidate Obama more vulnerable to GOP criticism that he cares more about green ideology than about job creation and energy security.

Former Shell Oil exec John Hofmeister nailed it: ”It’s much easier to avoid a decision than to make a decision,” and delay allows Obama to dangle the hope before each group that he’ll eventually decide in their favor.

This accountability-avoidance strategy might even induce environmentalists and labor to work harder for Obama’s re-election, the implicit deal on offer being that Obama will approve or disapprove the pipeline in 2013 depending on which group delivers more campaign contributions and votes in 2012.

All the more reason, then, for friends of affordable energy to lampoon Obama’s indecision as playing politics with the nation’s economic and energy future.