Having dealt with what looks to be the less contentious preferences as to how the NDP should look to build itself up from within, I'll move on to the question of whether and how the NDP should be relating to the other parties on Canada's political scene.
I've used the "unite the left behind the NDP" tag on a couple of posts before, and it nicely encapsulates what the party should be seeking to do.
I'll note however that the NDP focus doesn't mean ignoring the other federal parties or their supporters. Instead, it means continuing to work with other parties and their supporters where along with actors in the progressive movement where there's agreement on specific issues. And once there's been either a significant achievement or a loss that's come about due to a lack of combined political power, that's the time to seek to persuade the other actors involved both that a unified effort is required to push a progressive agenda, and that the NDP is the best vehicle for getting the job done done.
In contrast, the idea of a formal party merger is almost certainly a non-starter. The most often-mooted scenario involving the Libs simply leaves far too much likelihood that the NDP's current strength, like the progressive wing within the existing Libs, would simply be drowned out by the traditional dominance of business Libs when it comes time to decide what priorities to pursue. Which means that any merger would be almost certain to spawn another party to provide exactly the kind of voice the NDP now offers.
That isn't to say that the most obvious source of strength for the NDP is anything but the progressive Libs who for now have hooked onto a party which they see as more likely to take power. But the draw for those people has to be a strengthened NDP from other sources to persuade them that they don't have to accept playing second fiddle to the centre-right in order to win power.
Slightly more likely would be the possibility of joining forces with the Greens. But I'd want to see some awfully compelling reason to think that a combined party would actually have a strong likelihood of winning a wider cross-section of support than the NDP does already to make it worth the effort of fusing the two party structures.
Perhaps most intriguing is the question of whether the Bloc could be largely brought on board. If leftish Bloc members have any interest in joining a Canada-wide government in the making in order to boost progressive efforts both inside and outside Quebec, then the balance of risks and rewards would look to be by far the most favourable.
The problem for now, though, is that with both the Bloc and the NDP looking to be fairly satisfied with the recent election results, it's hard to see either wanting to take the risk involved in proposing a merger with part or all of the other. And indeed the NDP could reasonably figure that it's best off working to siphon off Bloc supporters individually to take over if it expects the Bloc to lose strength naturally, rather than pushing now for a formal alliance which might not play well elsewhere.
Of course, there are also options short of a complete merger. But those would likely raise many of the same problems as a merger with less of the rewards - making them too into a less viable option for now than simply working to build the NDP as a magnet for progressive values.
In sum, the NDP certainly should be building connections into all of the other "left" parties, and continuing to frame a message of unity similar to the Unite 4 Change concept which received some mention during the most recent campaign. But its efforts are almost certainly better directed toward winning individual supporters one by one, rather than looking to any formal merger as a short cut to the same final goal.
(Edit: fixed title.)