As someone who has voted for both the Liberals and the NDP, I think I can approach this debate without the clutter of partisanship. The criticism of the NDP seems to resolve around this premise that supporters are rigid idealists, who lack the pragmatism necessary to be a viable alternative. The argument implies a stubborn philosophy that only attracts purists who will never build the necessary coalitions to govern.
I think it a fair point to suggest that the NDP does adhere to certain concrete ideals and their policy positions reflect their basic tenets. There are occasions where the NDP appears elitist and holier than thou, I would suggest Layton's recent debate performances serve as examples. The perceived purity is partly a function of not having to govern, which gives the NDP an appearance of moral superiority, with a dash of detachment from practicality. However, despite the shortcomings of perpetual opposition, it is an unfair criticism to attack the NDP for holding firm ideals.
It is ironic that the NDP is attacked by Liberals for their ideals, when in fact the main obstacle Liberals face moving forward is their perceived hyper pragmatism, at the expense of consistent philosophy. The Conservative Party has a clear set of principles, not much different from their NDP counterparts. It is the Liberal Party that seems idea challenged, which may partially explain the bleeding of supporters to the NDP on the left, and the Conservatives from the center. People, whether they agree or disagree, know where the NDP stands on most issues. With the Liberals, their arguments lately revolve around what is wrong with others, as opposed to what is right with them.
It is folly to suggest that the NDP is forever relegated to a minor player in federal politics. It is also erroneous to make the claim that if the NDP ever were to usurp the Liberals, the new configuration would simply mirror the vanquished. Is the new Conservative Party a replica of the old Progressive Conservatives? There are the obvious similarities, but you can also point to profound differences. The left, center left, will always be the same, but how a party conducts itself is an open question.
Pragmatism is a necessary tool to be effective in politics. The NDP may have some lessons to learn in this regard if they are to move forward. However, equating the demand for pragmatism with the need to abandon core ideals is a dangerous suggestion. Where has constant pragmatism left the Liberal Party? You could suggest that the Liberal Party is relatively soulless in a historical context, as a result of always bending and compromising. If you compromise too much, water down your rhetoric to the point of mushy politico speak, you project nothingness and are left to employ scare tactics and other unseemly angles.
The main reason why I voted NDP this last election is twofold. First, I liked the NDP platform, it presented a positive agenda for moving forward. Despite the fact that Layton's constant peacock act was a distinct turnoff, overall the party had a vision. The Liberals on other hand, rarely offered policy, instead focusing on why we should fear Harper and how we were wasting our votes with the NDP. How can get excited about ideas and vision, when we are bombarded with pure politics? So, instead of bashing the NDP for hurting Liberals, Liberals are better served looking at what is the NDP appeal and formulating policy that attracts soft supporters. And, the NDP shouldn't allow itself to be preoccupied with bashing the Liberals as a means to gain support, instead it should offer its program on its own merits.