Talk about cutting their own throats! Besides the oil, half the north western USA depends on all the natural gas coming out of Alberta as well. That eed won't change and go away. As for the oil, there is no shortage of markets for it. It will just flow east instead.
Obama would also have to "carbon cap" his pal from south America, whose tar is even thicker than Alberta oil sands tar. I'm sure Chavez would just LOVE Obama to slap carbon taxes on his already worthless oil, trading below $36 a barrel, which for Chavez, is below cost of recovery, plus he has a lot of it refined in the USA.
If the price gets any lower, it will reach the non-profit zone in Canada as well, and the oil companies will just shut down operations. I think it's somewhere around $15-$20 a barrel.
Obama's carbon tax has a huge potential to cause severe gas shortages in the USA, by cutting off our supplies.
(side note, Canadian news is on showing Obama's "fans" cheering "O- ba- ma" in Canada. just a bunch of brainwashed kids, 50 or so, hard to tell with those tight camera shots, bussed in by force from schools, and a few muzzies. Woopie. Canadian media really blew this 'event' ) -20c doesn't help either.