I have predicted that Al Gore won’t endorse a candidate during the primary. I still think that’s probably true, and appropriate. But I’m starting to wonder.

What if Obama’s momentum — from SC and his recent endorsements — gives him just enough juice to reach near-parity with Clinton on Feb. 5, where she’s long been thought to have a substantial advantage? What if their campaigns stay in a close dogfight for weeks or months afterward, even leading up to the convention?

In a situation like that, tempers and passions will run high, every advantage will be pressed, and press scrutiny will be intense. Small events could make a big difference.

Enter Al Gore. If he has a chance to make an influential endorsement, possibly even to nudge Obama to victory, does he have the willpower to refrain? I don’t see how. It would be such sweet balance to his botched endorsement of Howard Dean in ’04. Like Ted Kennedy, Gore would become a huge fish in the comparatively small(er) pond of Obama’s powerful backers. He would enter 2009 with the full power of an historic new presidency at his back. Imagine what could be done with that power. Gore as climate envoy? Climate czar? Climate secretary?

In that event, Gore would have achieved a balance between the conflicting demands of his conscience. He would have the freedom to be a focused advocate and change public opinion, alongside the power of government to affect real change. Best of all, he could get there without the inanities and indignities of a political campaign.

If the Dem. primary reaches the point where Gore could become kingmaker, I suspect the temptation will be irresistible.