Look at the polls. Mark Carney gained almost entirely from the NDP to tie the conservatives. The Conservatives did not lose a vote.
If I was the NDP, that would piss me off. But they need to ask themselves, who do they want to win the election. It is very clearly not going to them. And, if they dunk on Mark Carney too much, it may not be him either.
Would the NDP prefer Mark Carney or Pollivere? They need to decide because, if the libs and NDP are stuck in a zero sum game, it may actually be the NDP that gets to decide the next election. The conservative vote appears locked in. The only question is how the everybody else is going to vote.