[youtube http://www.youtube.com/watch?feature=player_detailpage&v=PKAMeCpz-Jw]

NextGen Climate Action, the group founded by billionaire climate-action booster Tom Steyer, had submitted the ad to run on D.C.-area NBC affiliate WRC-TV during Obama’s Tuesday appearance on The Tonight Show, with the aim of reaching the influential inside-the-Beltway crowd. But at the last minute Tuesday evening, the station informed NextGen that the ad wouldn’t run after all, because it violated guidelines as “an attack of a personal nature.”

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The ad does feature an actor playing TransCanada CEO Russ Girling as a disingenuous, over-the-top oil baron at his, well, oiliest. But rather than defaming him as a serial sexter or making another such “personal” attack, it skewers farfetched claims Girling and his company have put forward about the Keystone XL pipeline’s economic benefits.

The Hill published a story about the ad Tuesday afternoon, before it was scrapped, that included criticism from Oil Sands Fact Check, a group that supports the pipeline. Now, according to Politico’s Morning Energy , NextGen wants NBC to sign an affidavit swearing it didn’t drop the ad as a result of industry pressure.

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This doesn’t mean NBC is staying out of the pipeline fight altogether. The network ran a pro-Keystone ad this past Sunday during Meet the Press. And it’s not like TransCanada’s voice is being drowned out by anti-pipeline advertising; the company launched a multi-platform ad campaign in the capital and around the country a couple weeks ago, and is even sponsoring Politico Playbook this week. And don’t forget that the Canadian government itself is shelling out millions for its own pro-pipeline campaign aimed at the D.C. bubble.