We can't rule O"Leary out but he has several hurdles to overcome unlike some other populist leaders we're familiar with.  First, he has to gain over 50% of the leadership vote on the ranked ballot system.  It's not a matter of just having the most votes.  There will be a healthy number of "anybody but O'Leary" votes.  Second, as each riding has an equal weight, he can't win just by signing up large numbers of disaffected rural people, as happened in the USA.  And 20% or more of the ridings are in Quebec, so he may have to get his 51% out of the remaining 80% ... that works out to almost two thirds of the ROC vote.