The NDP is seen to be the one with the toughest hill to climb. The party faithful believes that the NDP lost ground because it allowed itself to be outmanoeuvred by the Liberal Party -- on the left. The leadership contest is an opportunity to see which of the candidates are seriously listening to the expressed desire of the rank and file to move the party to the left.
The reason why a candidate like Angus is so interesting is because the new conventional wisdom is that there is no conventional wisdom anymore. A self-described socialist almost won the nomination for president of the United States, and probably would have won if the party he ran under did not work tirelessly against him. So the prospect of a true left-leaning politician inspiring voters from various sub-political persuasions no longer seems so far fetched.