There is no real left or right paradigm; it is an illusion, like in the book Flat Land or the film The Matrix. It's at least 2 dimensional: up/down and left/right. The "far left" today doesn't even get press coverage - the Democratic party doesn't represent them; just tries to sucker them for votes. see http://politicalcompass.org/
Characterizing the correct answer as left/right is ignoring the whole problem and debating empty propaganda.
Keystone helps sell shale oil cheaper. You just buy into the defeatist propaganda of the corporations to stand to gain (along with your so called "right" who were purchased and some "left" also who were purchased. The real reason lawyers make good politicians is they argue whatever position their boss wants like they believe it themselves.)
Higher costs for shale will delay it; hopefully, long enough to address demand with cheaper alternatives or enough sanity to ban it... Asbestos is cheap and we stopped using that! Assuming that oil is going to burn is as foolish as keeping the asbestos mines open in the middle of that debate (which was settled in science years before politics caught up; thank the vested interest lobby...) The cynical and wise strategic move is to STALL it out as long as possible so they don't invest in more expensive alternative routes - making it even less cost effective when keystone is stopped. That strategy does the most to stop them. (note: I'm not saying Obama's clever. It is a really clever plan and he just happens to be doing the same thing, so far.)
Extremists are never happy; don't know why you think giving each something they want is going to change anything!