It's the NDP that would suffer most if it fully rationalized its election strategy in cooperation with the Liberals outside of full merger. In almost every instance, second place Liberal candidates garnered more votes than the NDP candidate in key ridings and as a result, the two parties would be better off if the NDP didn't run a candidate at all.
In short, a formal merger is in the NDP's best interest while a coalition works best for the Liberals.
Horse hockey. Saying the other guy would do better folding their tent completely is utter nonsense, made all the more silly by saying it would only be temporary. In many seats, particularly out west, the NDP consistently finishes ahead. Out West, where the Liberals are weakest, some voters go from Conservative to NDP and back. If this is the best that you Liberals can come up with then its best to announce to the world that yet again the Liberals are talking out of both sides of their mouth. Call their bluff as I said -without having to commit ourself first.