While some younger activists have vowed they won’t rally around Obama on the fundraising or get-out-the-vote fronts if he gives the pipeline a thumbs-up, few can imagine them jumping parties to cast their support for the likes of Texas Gov. Rick Perry or former Godfather’s Pizza chief executive officer Herman Cain.
"With nobody challenging him in the primaries, Obama is aware he's the only guy they've got," Nordhaus said. "Successful candidates have to hold on to their base and do well with those in the middle. Obama hasn't figured out how to hang on to his base. At the end of the day, the election coming up will be determined by independent and moderate, undecided swing voters."
Obama's message to environmentalists might just be that he has already expended his conservation capital and it has contributed in putting him on the political ropes.
"The environmentalists have tried to make the battle over the pipeline more salient than it is," Nordhaus said, adding that this is just another pipeline among the hundreds that already crisscross the nation. "Obama has made big bets on what the environmentalists wanted, and it hasn't paid off for him."
By insisting that office seekers pass an environmental purity test, he said, conservationists could end up alienating even eco-friendly candidates.
"If environmentalists are going to keep being disappointed with their champions, then quite frankly those champions are going to say that it's not worth delivering," Nordhaus said. "The costs are too high and there's very little evidence that this constituency can move votes and get people elected in swing districts."