In a nutshell? Republicans have always been pro-business, and Democrats who opposed the pipeline saw massive losses in the recent midterms, and the ones remaining are scared. That said, I'm not entirely sure I oppose the pipeline. I haven't seen concrete evidence it'll harm the environment (the oil is going to be produced anyway; so impose strict regulations to prevent habitat destruction). I vehemently oppose NIMBYism. America's infrastructure is decrepit. Every time someone considers a nuclear plant, HSR, or high voltage lines, NIMBYs make the cost untenable. Oil pipelines aren't exactly the infrastructure I'd like to see, but it's something. Personally, I think the best route would be to permit the pipeline with accompanying regulation imposing inordinate penalties for environmental damage, and permitting nuclear plants. The same people that NIMBY over nuclear are voting for the pipeline. Fine – they can have their pipeline, if we can also drop a thorium reactor in their "backyard."Why are both parties going all out to get such a crappy deal?